tpm2_hmac not working with symmetric key

[bharath1294]

I am trying to load AES256 key and want to calculate dgst using sha1.

Commands used:
openssl rand -out aes-128.key 16
openssl rand -out challenge.bin 16
tpm2_loadexternal -G aes128 -r aes-128.key -c key_handle
name: 000bb3847c63c273860a2ea7da767bec90db8b339e90ee28391cb30533ecbb05b084
tpm2_hmac -c key_handle -g sha1 -o response.bin challenge.bin
WARNING:esys:src/tss2-esys/api/Esys_HMAC.c:300:Esys_HMAC_Finish() Received TPM Error
ERROR:esys:src/tss2-esys/api/Esys_HMAC.c:100:Esys_HMAC() Esys Finish ErrorCode (0x000002d2)
ERROR: Esys_HMAC(0x2D2) - tpm:parameter(2):unsupported or incompatible scheme
ERROR: Unable to run tpm2_hmac

[JuergenReppSIT]

At #1597 (comment) you will find how to import a symmetric key for HMAC computation. If you need sha1 you have to use -G hmac:sha1 for the import command.

[bharath1294]

Hi @JuergenReppSIT Thanks for responding, however i have one more issue. I want to calculate using sha1 and the comment you mentioned defaults to sha256 eventhough i change the parameter. Can you share how to enable the command to use sha1

Command: tpm2_import -C primary.ctx -G hmac -gsha1 -i aes-128.key -u aes-128.pub -r aes-128.priv

name-alg:
value: sha1
raw: 0x4
attributes:
value: userwithauth|sign
raw: 0x40040
type:
value: keyedhash
raw: 0x8
algorithm:
value: hmac
raw: 0x5
hash-alg:
value: sha256
raw: 0xb

[JuergenReppSIT]

you should use:
tpm2_import -C primary.ctx -G hmac:sha1 -gsha1 -i aes-128.key -u aes-128.pub -r aes-128.priv
`