RSA Security 5 manual BIntegerBits

B_IntegerBits

B_IntegerBits

unsigned int B_IntegerBits (
unsigned char *integer,		/* canonical integer */
unsigned int	integerLen	/* length in bytes */
);

Description

B_IntegerBits returns the number of significant bits in an arbitrary-length integer, where integer points to an unsigned byte array, most significant byte, first and integerLen gives its length. Leading zeroes are ignored. The integer is considered unsigned; that is, the most-significant bit is counted and is not considered a sign bit. If integerLen is zero, integer is ignored and B_IntegerBits returns zero. A typical application uses B_IntegerBits to determine the key size in bits of an RSA key by passing in the modulus.

This routine can be used to examine the value of a large integer such as the ones returned by B_GetKeyInfo for KI's like KI_RSAPublic.

Return value

B_IntegerBits returns the number of significant bits in integer.

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