How might clock synchronization work with RSA SecurID tokens?

How does the crypto in modern RSA SecurIDs work?

• According to a message board post in comp.security.misc, current-generation RSA SecurID hardware uses AES in ECB mode to hash the following: 128-bit token-specific random seed 64-bit standard ISO representation of the current time - (year/month/day/hour/minute/second 32-bit token-specific salt (the serial number of the token) 32-bits of padding (reserved for future use) The output of the hash is 6-8 digits or alphanumerics long and is regenerated every 60 seconds. ref: https://groups.google.com/group/comp.security.misc/msg/2de1eb5e8a73469a?dmode=source&hl=en Is this information correct? Is there any documentation, academic papers, or specifications for the current SecurID algorithm available publicly?

• Answer:

  Some good explanations as a result of the RSA hack: a SecurID is a display, a clock T, a secret key K, and a keyed cryptographic hash function H, all in a tamper-resistant package. Every 30-60 seconds, the token calculates H(K, T) and displays the result on the screen. When you log in, you supply your userid, the displayed value, and a PIN. The system consults one database to map your userid to the serial number of your token; it consults another to find the secret key for your token. It then does the same H(K, T) calculation to make sure the results match what you sent; it also checks your PIN. If everything is ok, the login is successful. https://www.cs.columbia.edu/~smb/blog//2011-03/2011-03-18.html The crypgographic algorithm used to calculate H is AES http://www.oxid.it/ca_um/topics/rsa_securid_token_calculator.htm You have listed the lengths and details of the other values involved.