IBM Crypto Education Community

Hi Group,

I have an application that needs to verify a digital signature using an RSA public key. The portion of the application that generates the signature provides the modulus (N) and public exponent (E) so I'm trying to use PKA Key Token Build (CSNDPKB) with the RSA-PUBL option to build an operational public key token that can be used in Digital Signature Verify (CSNDDSV). I'm a little confused by the ICSF manual as to which values need to be concatenated to build the key structure. Here's a REXX snippet of the code that build key structure.....however with a 512 byte modulus the structure length is 521 bytes which exceeds the limit for RSA-PUBL option. Any thoughts on how to build the key structure with a 512 byte modulus?

Keystruct      =  d2c(mod_len_in_bits,2), 
               || d2c(mod_len_in_bytes,2),
               || d2c(exp_len_in_bytes,2),
               || '0000'x,                
               || decoded_modulus,        
               || decoded_exponent        

Thanks,

Larry

Hi Larry,

Apparently I missed the notification for this question. I'll post a general sample showing the kvs and share a link here for others.

Here's a link to a Rexx sample showing how to import a 4096-bit RSA public key... https://www.ibm.com/developerworks/community/blogs/79c1eec4-00c4-48ef-ae2b-01bd8448dd6c/entry/Rexx_Sample_Import_a_4096_bit_RSA_Public_Key