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Digital_Signature_Generate CCA Release 2.54
hash_length
The hash_length parameter is a pointer to an integer variable containing the
number of bytes of data in the hash variable.
hash
The hash parameter is a pointer to a string variable containing the information
to be signed.
Notes:
1. For ISO-9796, the information identified by the hash parameter must be
less than or equal to one-half of the number of bytes required to contain
the modulus of the RSA key. Although ISO 9796-1 allows messages of
arbitrary bit length up to one-half of the modulus length, this verb requires
the input text to be a byte multiple up to the correct maximum length.
2. For PKCS-1.0 or PKCS-1.1, the information identified by the hash
parameter must be at least 11 bytes shorter than the number of bytes
required to contain the modulus of the RSA key, and should be the ANS.1
BER encoding of the hash value.
You can create the BER encoding of an MD5 or SHA-1 value by
prepending these strings to the 16-byte or 20-byte hash values,
respectively:
MD5 X'3020300C 06082A86 4886F70D 02050500 0410'
SHA-1 X'30213009 06052B0E 03021A05 000414'
3. For ZERO-PAD, the information identified by the hash parameter must be
less than or equal to the number of bytes required to contain the modulus
of the RSA key.
4. See “Formatting Hashes and Keys in Public-Key Cryptography” on
page D-19 for a discussion of hash formatting methods.
signature_field_length
The signature_field_length parameter is a pointer to an integer variable
containing the number of bytes of data in the signature_field variable. On
output, if the size is sufficient, the variable contains the actual length of the
digital signature returned by the verb. The maximum length is 256 bytes.
signature_bit_length
The signature_bit_length parameter is a pointer to an integer variable
containing the number of bits of data of the digital signature returned in the
signature_field variable.
signature_field
The signature_field parameter is a pointer to a string variable containing the
stored digital signature. Unused bytes at the right of the field are undefined
and should be ignored. The digital signature bit-field is in the low-order bits of
the byte string containing the digital signature.
Required Commands
The Digital_Signature_Generate verb requires the Digital Signature Generate
command (offset X'0100') to be enabled in the hardware.
4-6 IBM 4758 CCA Basic Services, Release 2.54, February 2005