ANSI X9.31-1998 pdf download Digital Signatures Using Reversible Public Key Cryptography for the Financial Services Industry (rDSA)
1. SCOPE
This standard, adapted from ISO/IEC 9796-2 [2] and ISO/IEC 14888-3 [16], defines a method for digital signature (signature) generation and verification for the protection of financial messages and data using reversible public key cryptography systems without message recovery. In addition, this rDSA Standard provides the criteria for the generation of public and private keys required by the algorithm and the procedural controls required for the secure use of the algorithm.
This standard guards against breaking the private key via certain factoring attacks. In particular, this standard guards against Pollard P-1 and P+1, and against difference of squares and related methods. The criterion used is that the amount of work needed for these attacks to succeed shall be at least 2 100 arithmetic operations. The way these attacks are guarded against is by the use of strong primes, and by use of criteria between the two primes, p and q, making up the public key, where n = pq.
The standard guards against more modern factoring attacks such as the Elliptic Curve Method, the Quadratic Sieve, and the Number Field Sieve, by requiring that the key be sufficiently large to make these attacks infeasible.
This standard allows primes to be generated either deterministically or probabilistically where:
— A number shall accepted as prime when a probabilistic algorithm which declares it to be prime is in error with probability less than 2
-100 .
— A deterministic prime shall be generated using a method specified in an ANSI X9 standard.
— A probabilistic prime shall be verified using primality tests specified in an ANSI X9 standard, such as X9.30-1, and as described in Appendix B: Generation of Parameters for rDSA of this standard.
Requirements placed upon the use of this standard, but out of scope are as follows:
— Digital signature generation and verification shall be used in conjunction with a hash algorithm specified in an ANSI X9 standard.
— Key generation shall be used in conjunctions with a random or pseudo-random number generator algorithm specified in an ANSI X9 standard.
There are various considerations to take into account for using reversible algorithms when implementing both digital signatures and encryption. Such considerations are not presented in this standard, but are provided in ANSI X9.44, Key Transport Using Reversible Public Key Cryptography for the Financial Industry.
Public key validation is not included in this version of the standard, but is anticipated to be added in the future.
2. DEFINITIONS, ABBREVIATIONS, AND REFERENCES
2.1 Definitions
DEFINITION MEANING
Certificate
(public key)
The public key and identity of an entity together with some other information,rendered unforgeable by signing the certificate with the private key of the certifying authority which issued that certificate.