The key for the HMAC depends on whether long-term or short-term credentials are in use. For long-term credentials, the key is 16 bytes: key = MD5(username ":" realm ":" SASLprep(password)) That is, the 16-byte key is formed by taking the MD5 hash of the result of concatenating the following five fields: (1) the username, with any quotes and trailing nulls removed, as taken from the USERNAME attribute (in which case SASLprep has already been applied); (2) a single colon; (3) the realm, with any quotes and trailing nulls removed; (4) a single colon; and (5) the password, with any trailing nulls removed and after processing using SASLprep. For example, if the username was 'user', the realm was 'realm', and the password was 'pass', then the 16-byte HMAC key would be the result of performing an MD5 hash on the string 'user:realm:pass', the resulting hash being 0x8493fbc53ba582fb4c044c456bdc40eb. For short-term credentials: key = SASLprep(password) where MD5 is defined in RFC 1321 [RFC1321] and SASLprep() is defined in RFC 4013 [RFC4013].
The key for the HMAC depends on whether long-term or short-term credentials are in use.
The key for the HMAC depends on whether long-term or short-term credentials are in use. For long-term credentials, the key is 16 bytes: key = MD5(username ":" realm ":" SASLprep(password)) That is, the 16-byte key is formed by taking the MD5 hash of the result of concatenating the following five fields: (1) the username, with any quotes and trailing nulls removed, as taken from the USERNAME attribute (in which case SASLprep has already been applied); (2) a single colon; (3) the realm, with any quotes and trailing nulls removed; (4) a single colon; and (5) the password, with any trailing nulls removed and after processing using SASLprep. For example, if the username was 'user', the realm was 'realm', and the password was 'pass', then the 16-byte HMAC key would be the result of performing an MD5 hash on the string 'user:realm:pass', the resulting hash being 0x8493fbc53ba582fb4c044c456bdc40eb. For short-term credentials: key = SASLprep(password) where MD5 is defined in RFC 1321 [RFC1321] and SASLprep() is defined in RFC 4013 [RFC4013].
The MESSAGE-INTEGRITY attribute contains an HMAC-SHA1 [RFC2104] of the STUN message. The MESSAGE-INTEGRITY attribute can be present in any STUN message type. Since it uses the SHA1 hash, the HMAC will be 20 bytes. The text used as input to HMAC is the STUN message, including the header, up to and including the attribute preceding the MESSAGE-INTEGRITY attribute. With the exception of the FINGERPRINT attribute, which appears after MESSAGE-INTEGRITY, agents MUST ignore all other attributes that follow MESSAGE-INTEGRITY.
https://tools.ietf.org/html/rfc5389#section-15.4
The key for the HMAC depends on whether long-term or short-term credentials are in use. For long-term credentials, the key is 16 bytes: key = MD5(username ":" realm ":" SASLprep(password)) That is, the 16-byte key is formed by taking the MD5 hash of the result of concatenating the following five fields: (1) the username, with any quotes and trailing nulls removed, as taken from the USERNAME attribute (in which case SASLprep has already been applied); (2) a single colon; (3) the realm, with any quotes and trailing nulls removed; (4) a single colon; and (5) the password, with any trailing nulls removed and after processing using SASLprep. For example, if the username was 'user', the realm was 'realm', and the password was 'pass', then the 16-byte HMAC key would be the result of performing an MD5 hash on the string 'user:realm:pass', the resulting hash being 0x8493fbc53ba582fb4c044c456bdc40eb. For short-term credentials: key = SASLprep(password) where MD5 is defined in RFC 1321 [RFC1321] and SASLprep() is defined in RFC 4013 [RFC4013].