diff --git a/Example/IrohaExample/ViewController.swift b/Example/IrohaExample/ViewController.swift
index 4706086fb..fe59a95cd 100755
--- a/Example/IrohaExample/ViewController.swift
+++ b/Example/IrohaExample/ViewController.swift
@@ -31,14 +31,14 @@ class ViewController: UIViewController {
     }()
 
     let adminPublicKey: IRPublicKeyProtocol = {
-        let adminPublicKeyData = NSData(hexString: Constants.adminPublicKey)! as Data
-        return IREd25519PublicKey(rawData: adminPublicKeyData)!
+        let adminPublicKeyData = try! NSData(hexString: Constants.adminPublicKey) as Data
+        return try! IRIrohaPublicKey(rawData: adminPublicKeyData)
     }()
 
     let adminSigner: IRSignatureCreatorProtocol = {
-        let adminPrivateKeyData = NSData(hexString: Constants.adminPrivateKey)! as Data
-        let adminPrivateKey = IREd25519PrivateKey(rawData: adminPrivateKeyData)!
-        return IREd25519Sha512Signer(privateKey: adminPrivateKey)!
+        let adminPrivateKeyData = try! NSData(hexString: Constants.adminPrivateKey) as Data
+        let adminPrivateKey = try! IRIrohaPrivateKey(rawData: adminPrivateKeyData)
+        return IRIrohaSigner(privateKey: adminPrivateKey)
     }()
 
     let assetId: IRAssetId = {
@@ -50,8 +50,8 @@ class ViewController: UIViewController {
     }()
 
     let userPublicKey: IRPublicKeyProtocol = {
-        let userPublicKeyData = NSData(hexString: Constants.newAccountPublicKey)! as Data
-        return IREd25519PublicKey(rawData: userPublicKeyData)!
+        let userPublicKeyData = try! NSData(hexString: Constants.newAccountPublicKey) as Data
+        return try! IRIrohaPublicKey(rawData: userPublicKeyData)
     }()
 
     let networkService: IRNetworkService = {
diff --git a/Example/Podfile.lock b/Example/Podfile.lock
old mode 100755
new mode 100644
index b9492043f..c174aa087
--- a/Example/Podfile.lock
+++ b/Example/Podfile.lock
@@ -24,13 +24,15 @@ PODS:
   - gRPC/Main (1.11.0):
     - gRPC-Core (= 1.11.0)
     - gRPC-RxLibrary (= 1.11.0)
-  - IrohaCommunication (3.4.1):
+  - IrohaCommunication (4.0.0):
     - BoringSSL (= 10.0.3)
     - gRPC-ProtoRPC (= 1.11.0)
-    - IrohaCrypto
+    - IrohaCrypto/Iroha (~> 0.3.0)
     - nanopb (= 0.3.8)
     - Protobuf (~> 3.5.0)
-  - IrohaCrypto (0.2.6)
+  - IrohaCrypto/Common (0.3.0)
+  - IrohaCrypto/Iroha (0.3.0):
+    - IrohaCrypto/Common
   - nanopb (0.3.8):
     - nanopb/decode (= 0.3.8)
     - nanopb/encode (= 0.3.8)
@@ -42,7 +44,7 @@ DEPENDENCIES:
   - IrohaCommunication (from `../`)
 
 SPEC REPOS:
-  https://github.com/CocoaPods/Specs.git:
+  trunk:
     - BoringSSL
     - gRPC
     - gRPC-Core
@@ -62,11 +64,11 @@ SPEC CHECKSUMS:
   gRPC-Core: 164639cd8ae18ca8b65477fafb2efbaecf4f181a
   gRPC-ProtoRPC: bb5fddf3424aa4fad74d76736578a79fe40e244e
   gRPC-RxLibrary: 26d53d1b1f306befd4ad4e15bd6de27839a82481
-  IrohaCommunication: 988a6f7fe468a863486e183fb8da617519ccb94e
-  IrohaCrypto: 4eb85b5edbf7667b5ffcef1b5104357f18ca8e81
+  IrohaCommunication: e53d340e9e787d920612248c34fbe4e4e5444fe8
+  IrohaCrypto: 5d518bd6fcde6d90be5e3f4d077d6cadb6e43fad
   nanopb: 5601e6bca2dbf1ed831b519092ec110f66982ca3
   Protobuf: 8a9838fba8dae3389230e1b7f8c104aa32389c03
 
 PODFILE CHECKSUM: 29089a97c3781ec366ef8266addf4289525ff849
 
-COCOAPODS: 1.8.4
+COCOAPODS: 1.9.0
diff --git a/IntegrationTests/IrohaContainer/IRBaseIrohaContainerTests.m b/IntegrationTests/IrohaContainer/IRBaseIrohaContainerTests.m
index 6ca047575..7abf45af2 100755
--- a/IntegrationTests/IrohaContainer/IRBaseIrohaContainerTests.m
+++ b/IntegrationTests/IrohaContainer/IRBaseIrohaContainerTests.m
@@ -45,13 +45,14 @@ - (void)initializePrimitives {
                                                      domain:_domain
                                                       error:nil];
 
-    NSData *rawPublicKey = [[NSData alloc] initWithHexString:@"313a07e6384776ed95447710d15e59148473ccfc052a681317a72a69f2a49910"];
-    NSData *rawPrivateKey = [[NSData alloc] initWithHexString:@"f101537e319568c765b2cc89698325604991dca57b9716b58016b253506cab70"];
+    NSData *rawPublicKey = [[NSData alloc] initWithHexString:@"313a07e6384776ed95447710d15e59148473ccfc052a681317a72a69f2a49910" error:nil];
+    NSData *rawPrivateKey = [[NSData alloc] initWithHexString:@"f101537e319568c765b2cc89698325604991dca57b9716b58016b253506cab70" error:nil];
 
-    _adminPublicKey = [[IREd25519PublicKey alloc] initWithRawData:rawPublicKey];
+    _adminPublicKey = [[IRIrohaPublicKey alloc] initWithRawData:rawPublicKey error:nil];
 
-    id<IRPrivateKeyProtocol> adminPrivateKey = [[IREd25519PrivateKey alloc] initWithRawData:rawPrivateKey];
-    _adminSigner = [[IREd25519Sha512Signer alloc] initWithPrivateKey:adminPrivateKey];
+    id<IRPrivateKeyProtocol> adminPrivateKey = [[IRIrohaPrivateKey alloc] initWithRawData:rawPrivateKey
+                                                                                    error:nil];
+    _adminSigner = [[IRIrohaSigner alloc] initWithPrivateKey:adminPrivateKey];
 }
 
 @end
diff --git a/IntegrationTests/Scenarious/IRAccountRestoreWithBatchTest.m b/IntegrationTests/Scenarious/IRAccountRestoreWithBatchTest.m
index 26e1f1f69..13766f403 100644
--- a/IntegrationTests/Scenarious/IRAccountRestoreWithBatchTest.m
+++ b/IntegrationTests/Scenarious/IRAccountRestoreWithBatchTest.m
@@ -29,11 +29,11 @@ - (void)setUp {
     _recoveryDomain = [IRDomainFactory domainWithIdentitifer:@"cmb.recovery" error:nil];
     _bankDomain = [IRDomainFactory domainWithIdentitifer:@"cmb" error:nil];
     _recoveryAccount = [IRAccountIdFactory accountIdWithName:@"recovery" domain:_recoveryDomain error:nil];
-    _recoveryKeypair = [[IREd25519KeyFactory new] createRandomKeypair];
-    _recoverySigner = [[IREd25519Sha512Signer alloc] initWithPrivateKey:_recoveryKeypair.privateKey];
+    _recoveryKeypair = [[IRIrohaKeyFactory new] createRandomKeypair:nil];
+    _recoverySigner = [[IRIrohaSigner alloc] initWithPrivateKey:_recoveryKeypair.privateKey];
     _clientAccount = [IRAccountIdFactory accountIdWithName:@"client" domain:_bankDomain error:nil];
-    _clientKeypair = [[IREd25519KeyFactory new] createRandomKeypair];
-    _clientSigner = [[IREd25519Sha512Signer alloc] initWithPrivateKey:_clientKeypair.privateKey];
+    _clientKeypair = [[IRIrohaKeyFactory new] createRandomKeypair: nil];
+    _clientSigner = [[IRIrohaSigner alloc] initWithPrivateKey:_clientKeypair.privateKey];
 }
 
 - (void)testAccountRestoreScenarioWithoutBatch {
diff --git a/IntegrationTests/Scenarious/IRCreateAccountTest.m b/IntegrationTests/Scenarious/IRCreateAccountTest.m
index 3245e04c3..264fc267f 100755
--- a/IntegrationTests/Scenarious/IRCreateAccountTest.m
+++ b/IntegrationTests/Scenarious/IRCreateAccountTest.m
@@ -17,9 +17,9 @@ - (void)testCreateAccount {
                                                                   domain:self.domain
                                                                    error:nil];
 
-    id<IRCryptoKeypairProtocol> keypair = [[[IREd25519KeyFactory alloc] init] createRandomKeypair];
+    id<IRCryptoKeypairProtocol> keypair = [[[IRIrohaKeyFactory alloc] init] createRandomKeypair:nil];
 
-    id<IRSignatureCreatorProtocol> newAccountSigner = [[IREd25519Sha512Signer alloc] initWithPrivateKey:keypair.privateKey];
+    id<IRSignatureCreatorProtocol> newAccountSigner = [[IRIrohaSigner alloc] initWithPrivateKey:keypair.privateKey];
 
     IRTransactionBuilder* builder = [IRTransactionBuilder builderWithCreatorAccountId:self.adminAccountId];
     builder = [builder createAccount:newAccountId publicKey:keypair.publicKey];
diff --git a/IntegrationTests/Scenarious/IRGetAssetsTest.m b/IntegrationTests/Scenarious/IRGetAssetsTest.m
index 6692bf32f..2134ccdfa 100644
--- a/IntegrationTests/Scenarious/IRGetAssetsTest.m
+++ b/IntegrationTests/Scenarious/IRGetAssetsTest.m
@@ -286,7 +286,12 @@ - (void)testCreateTransferThenFetchAssetWithZeroBalance {
                                                                 domain:self.domain
                                                                  error:&error];
 
-    id<IRCryptoKeypairProtocol> newKeypair = [[[IREd25519KeyFactory alloc] init] createRandomKeypair];
+    if (error) {
+        XCTFail();
+        return;
+    }
+
+    id<IRCryptoKeypairProtocol> newKeypair = [[[IRIrohaKeyFactory alloc] init] createRandomKeypair:&error];
 
     if (error) {
         XCTFail();
diff --git a/IntegrationTests/Service/IRCancellableTests.m b/IntegrationTests/Service/IRCancellableTests.m
index 475d31ff3..c83408638 100755
--- a/IntegrationTests/Service/IRCancellableTests.m
+++ b/IntegrationTests/Service/IRCancellableTests.m
@@ -61,7 +61,7 @@ - (nonnull NSData*)validTransactionHash {
                                                                   domain:self.domain
                                                                    error:nil];
 
-    id<IRCryptoKeypairProtocol> keypair = [[[IREd25519KeyFactory alloc] init] createRandomKeypair];
+    id<IRCryptoKeypairProtocol> keypair = [[[IRIrohaKeyFactory alloc] init] createRandomKeypair:nil];
 
     IRTransactionBuilder* builder = [IRTransactionBuilder builderWithCreatorAccountId:self.adminAccountId];
     builder = [builder createAccount:newAccountId publicKey:keypair.publicKey];
diff --git a/IrohaCommunication.podspec b/IrohaCommunication.podspec
index 4ddd89593..b8b001aa9 100755
--- a/IrohaCommunication.podspec
+++ b/IrohaCommunication.podspec
@@ -8,7 +8,7 @@
 
 Pod::Spec.new do |s|
   s.name             = 'IrohaCommunication'
-  s.version          = '3.5.0'
+  s.version          = '4.0.0'
   s.summary          = 'Helper classes to use for communication with Iroha blockchain.'
 
   s.homepage         = 'https://github.com/hyperledger/iroha-ios'
@@ -24,7 +24,7 @@ Pod::Spec.new do |s|
   s.private_header_files = 'IrohaCommunication/Classes/Private/**/*.h', 'ProtoGen/*.h'
   s.preserve_paths = 'ProtoGen/*.{h,m}'
 
-  s.dependency 'IrohaCrypto'
+  s.dependency 'IrohaCrypto/Iroha', '~> 0.3.0'
   s.dependency 'gRPC-ProtoRPC', '= 1.11.0'
   s.dependency 'Protobuf', '~> 3.5.0'
   s.dependency 'BoringSSL', '= 10.0.3'
diff --git a/IrohaCommunication/Classes/Private/IRBlockQueryRequestImpl.m b/IrohaCommunication/Classes/Private/IRBlockQueryRequestImpl.m
index c8ebadc63..79b7e3f85 100755
--- a/IrohaCommunication/Classes/Private/IRBlockQueryRequestImpl.m
+++ b/IrohaCommunication/Classes/Private/IRBlockQueryRequestImpl.m
@@ -124,25 +124,15 @@ - (nullable QueryPayloadMeta*)createPayload:(NSError **)error {
         return nil;
     }
 
-    NSData *sha3Data = [payloadData sha3:IRSha3Variant256];
+    NSData *sha3Data = [payloadData sha3:IRSha3Variant256 error:error];
 
     if (!sha3Data) {
-        if (error) {
-            NSString *message = @"Hashing function failed";
-            *error = [IRBlockQueryRequest errorWithType:IRQueryRequestErrorSigning
-                                                 message:message];
-        }
         return nil;
     }
 
-    id<IRSignatureProtocol> signature = [signatory sign:sha3Data];
+    id<IRSignatureProtocol> signature = [signatory sign:sha3Data error:error];
 
     if (!signature) {
-        if (error) {
-            NSString *message = @"Signing function failed";
-            *error = [IRBlockQueryRequest errorWithType:IRQueryRequestErrorSigning
-                                                 message:message];
-        }
         return nil;
     }
 
diff --git a/IrohaCommunication/Classes/Private/IRQueryRequestImpl.m b/IrohaCommunication/Classes/Private/IRQueryRequestImpl.m
index 248c905a7..e2267ec24 100755
--- a/IrohaCommunication/Classes/Private/IRQueryRequestImpl.m
+++ b/IrohaCommunication/Classes/Private/IRQueryRequestImpl.m
@@ -6,8 +6,8 @@
 #import "IRQueryRequestImpl.h"
 #import "Queries.pbobjc.h"
 #import "Primitive.pbobjc.h"
-#import "IrohaCrypto/NSData+SHA3.h"
 #import "NSDate+IrohaCommunication.h"
+#import <IrohaCrypto/NSData+SHA3.h>
 #import <IrohaCrypto/NSData+Hex.h>
 
 @implementation IRQueryRequest
@@ -148,25 +148,15 @@ - (nullable Query_Payload*)createPayload:(NSError **)error {
         return nil;
     }
 
-    NSData *sha3Data = [payloadData sha3:IRSha3Variant256];
+    NSData *sha3Data = [payloadData sha3:IRSha3Variant256 error:error];
 
     if (!sha3Data) {
-        if (error) {
-            NSString *message = @"Hashing function failed";
-            *error = [IRQueryRequest errorWithType:IRQueryRequestErrorSigning
-                                          message:message];
-        }
         return nil;
     }
 
-    id<IRSignatureProtocol> signature = [signatory sign:sha3Data];
+    id<IRSignatureProtocol> signature = [signatory sign:sha3Data error:error];
 
     if (!signature) {
-        if (error) {
-            NSString *message = @"Signing function failed";
-            *error = [IRQueryRequest errorWithType:IRQueryRequestErrorSigning
-                                          message:message];
-        }
         return nil;
     }
 
diff --git a/IrohaCommunication/Classes/Private/IRQueryResponse+Proto.m b/IrohaCommunication/Classes/Private/IRQueryResponse+Proto.m
index 317f026d1..0669f8d00 100755
--- a/IrohaCommunication/Classes/Private/IRQueryResponse+Proto.m
+++ b/IrohaCommunication/Classes/Private/IRQueryResponse+Proto.m
@@ -6,7 +6,8 @@
 #import "IRQueryResponse+Proto.h"
 #import "QryResponses.pbobjc.h"
 #import "IRQueryResponseAll.h"
-#import "IrohaCrypto/NSData+Hex.h"
+#import <IrohaCrypto/NSData+Hex.h>
+#import <IrohaCrypto/IRIrohaPublicKey.h>
 #import "IRTransactionImpl+Proto.h"
 #import "Primitive.pbobjc.h"
 #import "IRBatchInfo.h"
@@ -27,16 +28,10 @@ @implementation IRQueryResponseProtoFactory
         return nil;
     }
 
-    NSData *queryHash = [[NSData alloc] initWithHexString:pbResponse.queryHash];
+    NSData *queryHash = [[NSData alloc] initWithHexString:pbResponse.queryHash
+                                                    error:error];
 
     if (!queryHash) {
-        if (error) {
-            NSString *message = @"Invalid query hash. Hex is expected.";
-            *error = [NSError errorWithDomain:NSStringFromClass([IRQueryResponseProtoFactory class])
-                                         code:IRQueryResponseFactoryErrorQueryHashInvalid
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
-
         return nil;
     }
 
@@ -239,27 +234,16 @@ @implementation IRQueryResponseProtoFactory
     NSMutableArray<id<IRPublicKeyProtocol>> *publicKeys = [NSMutableArray array];
 
     for (NSString *pbPublicKey in pbResponse.keysArray) {
-        NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbPublicKey];
+        NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbPublicKey error:error];
 
         if (!rawPublicKey) {
-            if (error) {
-                NSString *message = [NSString stringWithFormat:@"Invalid public key hex string %@", pbPublicKey];
-                *error = [NSError errorWithDomain:NSStringFromClass([IRQueryResponseProtoFactory class])
-                                             code:IRQueryResponseFactoryErrorInvalidAgrument
-                                         userInfo:@{NSLocalizedDescriptionKey: message}];
-            }
             return nil;
         }
 
-        id<IRPublicKeyProtocol> publicKey = [[IREd25519PublicKey alloc] initWithRawData:rawPublicKey];
+        id<IRPublicKeyProtocol> publicKey = [[IRIrohaPublicKey alloc] initWithRawData:rawPublicKey
+                                                                                error:error];
 
         if (!publicKey) {
-            if (error) {
-                NSString *message = [NSString stringWithFormat:@"Invalid public key %@", [queryHash toHexString]];
-                *error = [NSError errorWithDomain:NSStringFromClass([IRQueryResponseProtoFactory class])
-                                             code:IRQueryResponseFactoryErrorInvalidAgrument
-                                         userInfo:@{NSLocalizedDescriptionKey: message}];
-            }
             return nil;
         }
 
@@ -394,16 +378,9 @@ @implementation IRQueryResponseProtoFactory
     NSData *nextTransactionHash = nil;
 
     if (pbResponse.nextTxHash && pbResponse.nextTxHash.length > 0) {
-        nextTransactionHash = [[NSData alloc] initWithHexString:pbResponse.nextTxHash];
+        nextTransactionHash = [[NSData alloc] initWithHexString:pbResponse.nextTxHash error:error];
 
         if (!nextTransactionHash) {
-            if (error) {
-                NSString *message = [NSString stringWithFormat:@"Invalid transaction hash %@", pbResponse.nextTxHash];
-                *error = [NSError errorWithDomain:NSStringFromClass([IRQueryResponseProtoFactory class])
-                                             code:IRQueryResponseFactoryErrorInvalidAgrument
-                                         userInfo:@{NSLocalizedDescriptionKey: message}];
-            }
-
             return nil;
         }
     }
@@ -480,27 +457,15 @@ @implementation IRQueryResponseProtoFactory
             return nil;
         }
         
-        NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbPeer.peerKey];
+        NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbPeer.peerKey error:error];
         
         if (!rawPublicKey) {
-            if (error) {
-                NSString *message = [NSString stringWithFormat:@"Invalid public key hex string %@", pbPeer.peerKey];
-                *error = [NSError errorWithDomain:NSStringFromClass([IRQueryResponseProtoFactory class])
-                                             code:IRQueryResponseFactoryErrorInvalidAgrument
-                                         userInfo:@{NSLocalizedDescriptionKey: message}];
-            }
             return nil;
         }
         
-        id<IRPublicKeyProtocol> publicKey = [[IREd25519PublicKey alloc] initWithRawData:rawPublicKey];
+        id<IRPublicKeyProtocol> publicKey = [[IRIrohaPublicKey alloc] initWithRawData:rawPublicKey error:error];
         
         if (!publicKey) {
-            if (error) {
-                NSString *message = [NSString stringWithFormat:@"Invalid public key %@", [queryHash toHexString]];
-                *error = [NSError errorWithDomain:NSStringFromClass([IRQueryResponseProtoFactory class])
-                                             code:IRQueryResponseFactoryErrorInvalidAgrument
-                                         userInfo:@{NSLocalizedDescriptionKey: message}];
-            }
             return nil;
         }
         
diff --git a/IrohaCommunication/Classes/Private/IRTransactionImpl+Proto.m b/IrohaCommunication/Classes/Private/IRTransactionImpl+Proto.m
index 15e5bd7d3..1fcab9b75 100755
--- a/IrohaCommunication/Classes/Private/IRTransactionImpl+Proto.m
+++ b/IrohaCommunication/Classes/Private/IRTransactionImpl+Proto.m
@@ -90,18 +90,7 @@ + (nullable IRTransaction*)transactionFromPbTransaction:(nonnull Transaction*)pb
         }
 
         for (NSString *pbReducedHash in pbTransaction.payload.batch.reducedHashesArray) {
-            NSData *batchHash = [[NSData alloc] initWithHexString:pbReducedHash];
-
-            if (!batchHash) {
-                if (error) {
-                    NSString *message = [NSString stringWithFormat:@"Invalid batch hash hex %@", pbReducedHash];
-                    *error = [NSError errorWithDomain:NSStringFromClass([IRTransaction class])
-                                                 code:IRTransactionProtoErrorInvalidArgument
-                                             userInfo:@{NSLocalizedDescriptionKey: message}];
-                }
-                return nil;
-            }
-
+            NSData *batchHash = [[NSData alloc] initWithHexString:pbReducedHash error:error];
             [batchHashes addObject:batchHash];
         }
     }
diff --git a/IrohaCommunication/Classes/Private/IRTransactionImpl.m b/IrohaCommunication/Classes/Private/IRTransactionImpl.m
index 72265bd8e..786f9e7a2 100755
--- a/IrohaCommunication/Classes/Private/IRTransactionImpl.m
+++ b/IrohaCommunication/Classes/Private/IRTransactionImpl.m
@@ -88,14 +88,9 @@ - (nullable NSData *)transactionHashWithError:(NSError **)error {
         return nil;
     }
 
-    NSData *sha3Data = [payloadData sha3:IRSha3Variant256];
+    NSData *sha3Data = [payloadData sha3:IRSha3Variant256 error:error];
 
     if (!sha3Data) {
-        if (error) {
-            NSString *message = @"Hashing function failed";
-            *error = [IRTransaction errorWithType:IRTransactionErrorHashing
-                                          message:message];
-        }
         return nil;
     }
 
@@ -239,14 +234,9 @@ - (nullable NSData *)batchHashWithError:(NSError **)error {
         return nil;
     }
 
-    NSData *sha3Data = [reducedPayloadData sha3:IRSha3Variant256];
+    NSData *sha3Data = [reducedPayloadData sha3:IRSha3Variant256 error:error];
 
     if (!sha3Data) {
-        if (error) {
-            NSString *message = @"Hashing function failed";
-            *error = [IRTransaction errorWithType:IRTransactionErrorHashing
-                                          message:message];
-        }
         return nil;
     }
 
@@ -352,25 +342,15 @@ - (nullable Transaction_Payload*)createPayload:(NSError **)error {
         return nil;
     }
 
-    NSData *sha3Data = [payloadData sha3:IRSha3Variant256];
+    NSData *sha3Data = [payloadData sha3:IRSha3Variant256 error:error];
 
     if (!sha3Data) {
-        if (error) {
-            NSString *message = @"Hashing function failed";
-            *error = [IRTransaction errorWithType:IRTransactionErrorSigning
-                                          message:message];
-        }
         return nil;
     }
 
-    id<IRSignatureProtocol> signature = [signatory sign:sha3Data];
+    id<IRSignatureProtocol> signature = [signatory sign:sha3Data error:error];
 
     if (!signature) {
-        if (error) {
-            NSString *message = @"Signing function failed";
-            *error = [IRTransaction errorWithType:IRTransactionErrorSigning
-                                          message:message];
-        }
         return nil;
     }
 
diff --git a/IrohaCommunication/Classes/Private/IRTransactionStatusResponseImpl+Proto.m b/IrohaCommunication/Classes/Private/IRTransactionStatusResponseImpl+Proto.m
index 236f1b92b..2110bebbe 100755
--- a/IrohaCommunication/Classes/Private/IRTransactionStatusResponseImpl+Proto.m
+++ b/IrohaCommunication/Classes/Private/IRTransactionStatusResponseImpl+Proto.m
@@ -10,16 +10,9 @@
 @implementation IRTransactionStatusResponse (Proto)
 
 + (nullable instancetype)statusResponseWithToriiResponse:(nonnull ToriiResponse *)toriiResponse error:(NSError **)error {
-    NSData *transactionHash = [[NSData alloc] initWithHexString:toriiResponse.txHash];
+    NSData *transactionHash = [[NSData alloc] initWithHexString:toriiResponse.txHash error:error];
 
     if (!transactionHash) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Unexpected hex transaction hash %@", toriiResponse.txHash];
-            *error = [NSError errorWithDomain:@"IRTransactionStatusResponseProtoError"
-                                         code:IRTransactionStatusResponseProtoErrorInvalidField
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
-
         return nil;
     }
 
diff --git a/IrohaCommunication/Classes/Private/Models/IRBlock+Proto.m b/IrohaCommunication/Classes/Private/Models/IRBlock+Proto.m
index 9405c8c04..15ecdd357 100755
--- a/IrohaCommunication/Classes/Private/Models/IRBlock+Proto.m
+++ b/IrohaCommunication/Classes/Private/Models/IRBlock+Proto.m
@@ -68,26 +68,19 @@ @implementation IRBlock (Proto)
     }
 
     for (NSString *pbRejectedHash in block.blockV1.payload.rejectedTransactionsHashesArray)  {
-        NSData *rejectedHash = [[NSData alloc] initWithHexString:pbRejectedHash];
+        NSData *rejectedHash = [[NSData alloc] initWithHexString:pbRejectedHash error:error];
 
         if (!rejectedHash) {
-            if (error) {
-                NSString *message = [NSString stringWithFormat:@"Can't parse rejected hash hex string: %@", pbRejectedHash];
-                *error = [IRBlock errorWithMessage:message];
-            }
             return nil;
         }
 
         [rejectedHashes addObject:rejectedHash];
     }
 
-    NSData *previousBlockHash = [[NSData alloc] initWithHexString:block.blockV1.payload.prevBlockHash];
+    NSData *previousBlockHash = [[NSData alloc] initWithHexString:block.blockV1.payload.prevBlockHash
+                                                            error:error];
 
     if (!previousBlockHash) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Can't parse previous block hash hex string: %@", block.blockV1.payload.prevBlockHash];
-            *error = [IRBlock errorWithMessage:message];
-        }
         return nil;
     }
 
diff --git a/IrohaCommunication/Classes/Private/Models/IRCommand+Proto.m b/IrohaCommunication/Classes/Private/Models/IRCommand+Proto.m
index e84771dab..a14634380 100755
--- a/IrohaCommunication/Classes/Private/Models/IRCommand+Proto.m
+++ b/IrohaCommunication/Classes/Private/Models/IRCommand+Proto.m
@@ -6,7 +6,8 @@
 #import "IRCommand+Proto.h"
 #import "Commands.pbobjc.h"
 #import "Primitive.pbobjc.h"
-#import "IrohaCrypto/NSData+Hex.h"
+#import <IrohaCrypto/NSData+Hex.h>
+#import <IrohaCrypto/IRIrohaPublicKey.h>
 
 @implementation IRCommandProtoFactory
 
@@ -105,15 +106,9 @@ @implementation IRCommandProtoFactory
         return nil;
     }
 
-    NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbCommand.peer.peerKey];
+    NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbCommand.peer.peerKey error:error];
 
     if (!rawPublicKey) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Invalid public key hex %@", pbCommand.peer.peerKey];
-            *error = [NSError errorWithDomain:NSStringFromClass([IRCommandProtoFactory class])
-                                         code:IRCommandProtoFactoryErrorInvalidArgument
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
         return nil;
     }
 
@@ -223,15 +218,9 @@ @implementation IRCommandProtoFactory
         return nil;
     }
 
-    NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbCommand.publicKey];
+    NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbCommand.publicKey error:error];
 
     if (!rawPublicKey) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Invalid public key hex %@", pbCommand.publicKey];
-            *error = [NSError errorWithDomain:NSStringFromClass([IRCommandProtoFactory class])
-                                         code:IRCommandProtoFactoryErrorInvalidArgument
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
         return nil;
     }
 
@@ -286,15 +275,10 @@ @implementation IRCommandProtoFactory
         return nil;
     }
 
-    NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbCommand.publicKey];
+    NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbCommand.publicKey
+                                                       error:error];
 
     if (!rawPublicKey) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Invalid public key hex %@", pbCommand.publicKey];
-            *error = [NSError errorWithDomain:NSStringFromClass([IRCommandProtoFactory class])
-                                         code:IRCommandProtoFactoryErrorInvalidArgument
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
         return nil;
     }
 
@@ -374,15 +358,9 @@ @implementation IRCommandProtoFactory
         return nil;
     }
 
-    NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbCommand.publicKey];
+    NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbCommand.publicKey error:error];
 
     if (!rawPublicKey) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Invalid public key hex %@", pbCommand.publicKey];
-            *error = [NSError errorWithDomain:NSStringFromClass([IRCommandProtoFactory class])
-                                         code:IRCommandProtoFactoryErrorInvalidArgument
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
         return nil;
     }
 
@@ -488,15 +466,9 @@ @implementation IRCommandProtoFactory
 
 + (nullable id<IRRemovePeer>)removePeerCommandFromPbCommand:(nonnull RemovePeer *)pbCommand
                                                       error:(NSError **)error {
-    NSData *rawPeerKey = [[NSData alloc] initWithHexString:pbCommand.publicKey];
+    NSData *rawPeerKey = [[NSData alloc] initWithHexString:pbCommand.publicKey error:error];
     
     if (!rawPeerKey) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Invalid public key hex %@", pbCommand.publicKey];
-            *error = [NSError errorWithDomain:NSStringFromClass([IRCommandProtoFactory class])
-                                         code:IRCommandProtoFactoryErrorInvalidArgument
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
         return nil;
     }
     
@@ -525,15 +497,9 @@ @implementation IRCommandProtoFactory
 }
 
 + (nullable id<IRPublicKeyProtocol>)createPublicKeyFromRawData:(nonnull NSData *)rawData error:(NSError **)error {
-    id<IRPublicKeyProtocol> publicKey = [[IREd25519PublicKey alloc] initWithRawData:rawData];
+    id<IRPublicKeyProtocol> publicKey = [[IRIrohaPublicKey alloc] initWithRawData:rawData error:error];
 
     if (!publicKey) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Invalid public key %@", [rawData toHexString]];
-            *error = [NSError errorWithDomain:NSStringFromClass([IRCommandProtoFactory class])
-                                         code:IRCommandProtoFactoryErrorInvalidArgument
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
         return nil;
     }
 
diff --git a/IrohaCommunication/Classes/Private/Models/IRPeerSignature+Proto.m b/IrohaCommunication/Classes/Private/Models/IRPeerSignature+Proto.m
index 4e6a2af6a..a607442c2 100755
--- a/IrohaCommunication/Classes/Private/Models/IRPeerSignature+Proto.m
+++ b/IrohaCommunication/Classes/Private/Models/IRPeerSignature+Proto.m
@@ -6,58 +6,34 @@
 #import "IRPeerSignature+Proto.h"
 #import "Primitive.pbobjc.h"
 #import <IrohaCrypto/NSData+Hex.h>
+#import <IrohaCrypto/IRIrohaSignature.h>
+#import <IrohaCrypto/IRIrohaPublicKey.h>
 
 @implementation IRPeerSignatureFactory (Proto)
 
 + (nullable id<IRPeerSignature>)peerSignatureFromPbSignature:(nonnull Signature *)pbSignature
                                                        error:(NSError *_Nullable*_Nullable)error {
-    NSData *rawSignature = [[NSData alloc] initWithHexString:pbSignature.signature];
+    NSData *rawSignature = [[NSData alloc] initWithHexString:pbSignature.signature error:error];
 
     if (!rawSignature) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Unexpected hex signature %@", pbSignature.signature];
-            *error = [NSError errorWithDomain:NSStringFromClass([IRPeerSignatureFactory class])
-                                         code:IRPeerSignatureFactoryProtoErrorInvalidArgument
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
-
         return nil;
     }
 
-    id<IRSignatureProtocol> signature = [[IREd25519Sha512Signature alloc] initWithRawData:rawSignature];
+    id<IRSignatureProtocol> signature = [[IRIrohaSignature alloc] initWithRawData:rawSignature error:error];
 
     if (!signature) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Invalid signature %@", pbSignature.signature];
-            *error = [NSError errorWithDomain:NSStringFromClass([IRPeerSignatureFactory class])
-                                         code:IRPeerSignatureFactoryProtoErrorInvalidArgument
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
         return nil;
     }
 
-    NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbSignature.publicKey];
+    NSData *rawPublicKey = [[NSData alloc] initWithHexString:pbSignature.publicKey error:error];
 
     if (!rawPublicKey) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Unexpected hex public key %@", pbSignature.publicKey];
-            *error = [NSError errorWithDomain:NSStringFromClass([IRPeerSignatureFactory class])
-                                         code:IRPeerSignatureFactoryProtoErrorInvalidArgument
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
-
         return nil;
     }
 
-    id<IRPublicKeyProtocol> publicKey = [[IREd25519PublicKey alloc] initWithRawData:rawPublicKey];
+    id<IRPublicKeyProtocol> publicKey = [[IRIrohaPublicKey alloc] initWithRawData:rawPublicKey error:error];
 
     if (!publicKey) {
-        if (error) {
-            NSString *message = [NSString stringWithFormat:@"Invalid public key %@", pbSignature.publicKey];
-            *error = [NSError errorWithDomain:NSStringFromClass([IRPeerSignatureFactory class])
-                                         code:IRPeerSignatureFactoryProtoErrorInvalidArgument
-                                     userInfo:@{NSLocalizedDescriptionKey: message}];
-        }
         return nil;
     }
 
diff --git a/IrohaCommunication/Classes/Public/Model/Common/IRPeer.h b/IrohaCommunication/Classes/Public/Model/Common/IRPeer.h
index b9d06d4b7..39be17770 100644
--- a/IrohaCommunication/Classes/Public/Model/Common/IRPeer.h
+++ b/IrohaCommunication/Classes/Public/Model/Common/IRPeer.h
@@ -5,7 +5,7 @@
 
 #import <Foundation/Foundation.h>
 #import "IRAddress.h"
-#import "IrohaCrypto/IRPublicKey.h"
+#import <IrohaCrypto/IRCryptoKey.h>
 
 
 @protocol IRPeer <NSObject>
diff --git a/IrohaCommunication/Classes/Public/Model/Common/IRPeerSignature.h b/IrohaCommunication/Classes/Public/Model/Common/IRPeerSignature.h
index ca8fea2d4..04552999a 100755
--- a/IrohaCommunication/Classes/Public/Model/Common/IRPeerSignature.h
+++ b/IrohaCommunication/Classes/Public/Model/Common/IRPeerSignature.h
@@ -4,8 +4,8 @@
  */
 
 #import <Foundation/Foundation.h>
-#import "IrohaCrypto/IRSignature.h"
-#import "IrohaCrypto/IRPublicKey.h"
+#import <IrohaCrypto/IRSignature.h>
+#import <IrohaCrypto/IRCryptoKey.h>
 
 @protocol IRPeerSignature <NSObject>
 
diff --git a/IrohaCommunication/Classes/Public/Model/IRCommand.h b/IrohaCommunication/Classes/Public/Model/IRCommand.h
index fb35976ab..6429ffcd9 100755
--- a/IrohaCommunication/Classes/Public/Model/IRCommand.h
+++ b/IrohaCommunication/Classes/Public/Model/IRCommand.h
@@ -14,7 +14,7 @@
 #import "IRGrantablePermission.h"
 #import "IRRoleName.h"
 #import "IRRolePermission.h"
-#import <IrohaCrypto/IRPublicKey.h>
+#import <IrohaCrypto/IRCryptoKey.h>
 
 @protocol IRCommand <NSObject>
 
diff --git a/IrohaCommunication/Classes/Public/Model/IRQueryResponse.h b/IrohaCommunication/Classes/Public/Model/IRQueryResponse.h
index 3e437e1ca..618d06c2e 100755
--- a/IrohaCommunication/Classes/Public/Model/IRQueryResponse.h
+++ b/IrohaCommunication/Classes/Public/Model/IRQueryResponse.h
@@ -11,7 +11,7 @@
 #import "IRRoleName.h"
 #import "IRRolePermission.h"
 #import "IRTransaction.h"
-#import "IrohaCrypto/IRPublicKey.h"
+#import <IrohaCrypto/IRCryptoKey.h>
 #import "IRAccountDetailRecordId.h"
 #import "IRPeer.h"
 #import "IRBatchInfo.h"
diff --git a/IrohaCommunication/Classes/Public/Model/IRSignable.h b/IrohaCommunication/Classes/Public/Model/IRSignable.h
index b6068f5ad..557f993d5 100755
--- a/IrohaCommunication/Classes/Public/Model/IRSignable.h
+++ b/IrohaCommunication/Classes/Public/Model/IRSignable.h
@@ -6,7 +6,7 @@
 #ifndef IRSignable_h
 #define IRSignable_h
 
-#import <IrohaCrypto/IRSignatureCreator.h>
+#import <IrohaCrypto/IRSignature.h>
 #import "IRPeerSignature.h"
 
 @protocol IRSignable <NSObject>
diff --git a/Tests/Model/IRPaginationTests.m b/Tests/Model/IRPaginationTests.m
index e83ccad52..2016c711c 100755
--- a/Tests/Model/IRPaginationTests.m
+++ b/Tests/Model/IRPaginationTests.m
@@ -13,10 +13,17 @@ @interface IRPaginationTests : XCTestCase
 @implementation IRPaginationTests
 
 - (void)testValidPagination {
-    NSData *itemHash = [[@"Test Hash" dataUsingEncoding:NSUTF8StringEncoding] sha3:IRSha3Variant256];
+    NSError *error = nil;
+
+    NSData *itemHash = [[@"Test Hash" dataUsingEncoding:NSUTF8StringEncoding] sha3:IRSha3Variant256
+                                                                             error:&error];
+
+    XCTAssertNil(error);
+
+    error = nil;
+
     UInt32 pageSize = 10;
 
-    NSError *error = nil;
     id<IRPagination> pagination = [IRPaginationFactory pagination:pageSize
                                                     firstItemHash:itemHash
                                                             error:&error];
diff --git a/Tests/Query/IRBlockQueryBuilderTests.m b/Tests/Query/IRBlockQueryBuilderTests.m
index ec1a7a2d8..d74fec9d2 100755
--- a/Tests/Query/IRBlockQueryBuilderTests.m
+++ b/Tests/Query/IRBlockQueryBuilderTests.m
@@ -60,10 +60,16 @@ - (void)testSignedWithDefaultCreatedTime {
     XCTAssertNil(query.peerSignature);
     XCTAssertEqualObjects(accountId.identifier, query.creator.identifier);
 
-    id<IRCryptoKeypairProtocol> keypair = [[[IREd25519KeyFactory alloc] init] createRandomKeypair];
-    id<IRSignatureCreatorProtocol> signer = [[IREd25519Sha512Signer alloc] initWithPrivateKey:keypair.privateKey];
+    error = nil;
+
+    id<IRCryptoKeypairProtocol> keypair = [[[IRIrohaKeyFactory alloc] init] createRandomKeypair:&error];
+
+    XCTAssertNil(error);
 
     error = nil;
+
+    id<IRSignatureCreatorProtocol> signer = [[IRIrohaSigner alloc] initWithPrivateKey:keypair.privateKey];
+
     id<IRBlockQueryRequest> signedQuery = [query signedWithSignatory:signer
                                                   signatoryPublicKey:keypair.publicKey
                                                                error:&error];
diff --git a/Tests/Query/IRQueryBuilderTests.m b/Tests/Query/IRQueryBuilderTests.m
index b74d5611f..5a9eeaa6e 100755
--- a/Tests/Query/IRQueryBuilderTests.m
+++ b/Tests/Query/IRQueryBuilderTests.m
@@ -108,8 +108,13 @@ - (void)testQueries {
         XCTAssertTrue([queryRequest.query conformsToProtocol:testCase.protocol]);
         XCTAssertNil(queryRequest.peerSignature);
 
-        id<IRCryptoKeypairProtocol> keypair = [[[IREd25519KeyFactory alloc] init] createRandomKeypair];
-        id<IRSignatureCreatorProtocol> signatory = [[IREd25519Sha512Signer alloc] initWithPrivateKey:[keypair privateKey]];
+        error = nil;
+
+        id<IRCryptoKeypairProtocol> keypair = [[[IRIrohaKeyFactory alloc] init] createRandomKeypair:&error];
+
+        XCTAssertNil(error, "Iroha key factory error: %@", [error localizedDescription]);
+
+        id<IRSignatureCreatorProtocol> signatory = [[IRIrohaSigner alloc] initWithPrivateKey:[keypair privateKey]];
 
         error = nil;
 
@@ -118,14 +123,15 @@ - (void)testQueries {
                                                                             error:&error];
 
         XCTAssertNotNil(signedQueryRequest.peerSignature);
-        XCTAssertNil(error);
+        XCTAssertNil(error, "Signing failed: %@", [error localizedDescription]);
 
         error = nil;
+
         NSData *rawQueryRequestData = [IRSerializationFactory serializeQueryRequest:signedQueryRequest
                                                                               error:&error];
 
         XCTAssertNotNil(rawQueryRequestData);
-        XCTAssertNil(error);
+        XCTAssertNil(error, "Serialization failed: %@", [error localizedDescription]);
     }
     
 }
diff --git a/Tests/Transaction/IRTransactionTests.m b/Tests/Transaction/IRTransactionTests.m
index be782e009..a3ed58e74 100755
--- a/Tests/Transaction/IRTransactionTests.m
+++ b/Tests/Transaction/IRTransactionTests.m
@@ -31,18 +31,23 @@ - (void)testTransactionBuildWithAllCommandsAndSingleSignature {
 
     error = nil;
 
-    id<IRCryptoKeypairProtocol> keypair = [[[IREd25519KeyFactory alloc] init] createRandomKeypair];
+    id<IRCryptoKeypairProtocol> keypair = [[[IRIrohaKeyFactory alloc] init] createRandomKeypair:&error];
+
+    XCTAssertNil(error, "Key pair generation failed: %@", [error localizedDescription]);
+
+    error = nil;
 
     id<IRTransaction> signedTransaction = [self createSignedFromTransaction:transaction
                                                                     keypair:keypair
                                                                       error:&error];
 
     XCTAssertNotNil(signedTransaction);
-    XCTAssertNil(error);
+    XCTAssertNil(error, "Signing failed: %@", [error localizedDescription]);
 
     error = nil;
 
-    id<IRSignatureCreatorProtocol> signatory = [[IREd25519Sha512Signer alloc] initWithPrivateKey:[keypair privateKey]];
+    id<IRSignatureCreatorProtocol> signatory = [[IRIrohaSigner alloc] initWithPrivateKey:[keypair privateKey]];
+
     id<IRPeerSignature> peerSignature = [transaction signWithSignatory:signatory
                                                     signatoryPublicKey:[keypair publicKey]
                                                                  error:&error];
@@ -54,7 +59,7 @@ - (void)testTransactionBuildWithAllCommandsAndSingleSignature {
     XCTAssertEqualObjects(peerSignature.signature.rawData, resultSignature.signature.rawData);
     XCTAssertEqualObjects(peerSignature.publicKey.rawData, resultSignature.publicKey.rawData);
 
-    IREd25519Sha512Verifier *verifier = [[IREd25519Sha512Verifier alloc] init];
+    IRIrohaSignatureVerifier *verifier = [[IRIrohaSignatureVerifier alloc] init];
     BOOL verified = [verifier verify:resultSignature.signature
                      forOriginalData:[transaction transactionHashWithError:nil]
                       usingPublicKey:resultSignature.publicKey];
@@ -77,7 +82,11 @@ - (void)testInitializationFromRawTransaction {
 
     error = nil;
 
-    id<IRCryptoKeypairProtocol> keypair = [[[IREd25519KeyFactory alloc] init] createRandomKeypair];
+    id<IRCryptoKeypairProtocol> keypair = [[[IRIrohaKeyFactory alloc] init] createRandomKeypair:&error];
+
+    XCTAssertNil(error, "Keypair creation failed: %@", [error localizedDescription]);
+
+    error = nil;
 
     id<IRTransaction> signedTransaction = [self createSignedFromTransaction:transaction
                                                                     keypair:keypair
@@ -128,7 +137,13 @@ - (void)testBatchInitialization {
     XCTAssertNotNil(batchHash);
     XCTAssertNil(error);
 
-    id<IRCryptoKeypairProtocol> keypair = [[[IREd25519KeyFactory alloc] init] createRandomKeypair];
+    error = nil;
+
+    id<IRCryptoKeypairProtocol> keypair = [[[IRIrohaKeyFactory alloc] init] createRandomKeypair:&error];
+
+    XCTAssertNil(error, "Keypair creation failed: %@", [error localizedDescription]);
+
+    error = nil;
 
     id<IRTransaction> signedTransaction = [self createSignedFromTransaction:transaction
                                                                     keypair:keypair
@@ -183,7 +198,7 @@ - (void)testBatchInitialization {
 
     id<IRRoleName> roleName = [IRRoleNameFactory roleWithName:VALID_ROLE error:nil];
 
-    id<IRCryptoKeypairProtocol> keypair = [[[IREd25519KeyFactory alloc] init] createRandomKeypair];
+    id<IRCryptoKeypairProtocol> keypair = [[[IRIrohaKeyFactory alloc] init] createRandomKeypair: nil];
 
     IRTransactionBuilder* builder = [IRTransactionBuilder builderWithCreatorAccountId:accountId];
     builder = [builder addAssetQuantity:assetId amount:amount];
@@ -218,7 +233,7 @@ - (void)testBatchInitialization {
                                                   keypair:(id<IRCryptoKeypairProtocol>)keypair
                                                     error:(NSError **)error {
 
-    id<IRSignatureCreatorProtocol> signatory = [[IREd25519Sha512Signer alloc] initWithPrivateKey:[keypair privateKey]];
+    id<IRSignatureCreatorProtocol> signatory = [[IRIrohaSigner alloc] initWithPrivateKey:[keypair privateKey]];
     return [transaction signedWithSignatories:@[signatory]
                           signatoryPublicKeys:@[[keypair publicKey]]
                                         error:error];