- From: Web Cryptography Working Group Issue Tracker <sysbot+tracker@w3.org>
- Date: Wed, 22 Aug 2012 20:34:57 +0000
- To: public-webcrypto@w3.org
crypto-ISSUE-27 (aes ctr): Specification of AES-CTR mode counter bits [Web Cryptography API] http://www.w3.org/2012/webcrypto/track/issues/27 Raised by: Ryan Sleevi On product: Web Cryptography API Under the AesCtrParams [1], callers can currently specify an initial value for the counter, as well as a length for how many bits are used for the block counter. Such a specification matches the PKCS#11 definition for AES-CTR, although other APIs such as CDSA, CryptoAPI, and CNG, do not support explicit counter mode, and instead only support ECB as a foundation for CTR. However, by only specifying the length in bits of the counter, it presumes that the counter bits are either in the most-significant or least-significant bytes. Different systems using AES-CTR may place the block counter in different places - some using the MSB, others using the LSB. Thus, should the API specify an 'offset' as well that, when combined with length, gives a clear position of where the block counter is (internally managed by the API), and where the message counter/nonce are (externally managed by the caller) [1] http://www.w3.org/2012/webcrypto/WebCryptoAPI/#dfn-AesCtrParams
Received on Wednesday, 22 August 2012 20:35:13 UTC