ANSI X9.30 [ANS93a] is the United States financial industry standard for digital signatures based on the federal Digital Signature Algorithm (DSA), and ANSI X9.31 [ANS93b] is the counterpart standard for digital signatures based on the RSA algorithm. ANSI X9.30 requires the SHA1 hash algorithm (see Question 100); ANSI X9.31 requires the MDC-2 hash algorithm [ISO92c].
A related document, X9.57 [ANS95], covers certificate management (see Question 123).