Re: Minimum length of secret key

James Couzens wrote:

>> What is minimum recommended length of the secret key used to generate
>> the cryptographic hash so that the secret key cannot be guesses by
>> cryptographic analysis of email addresses modified by SRS?

> 512 bits for SHA-160, and ideally they would be all truly random too.

SRS uses HMAC-SHA1 where the key is limited to 64 bits. What was the reason
to use HMAC-SHA1 instead of  SHA-1 applied to the concatenation of a secret
key (without length limit) and the string to hash?

Roger