Fix pk_write with EC key to use a constant size for the private value #314

Merged

gilles-peskine-arm merged 2 commits from pkwrite_ECPrivateKey_size-crypto into development

2019-11-08 12:30:52 -06:00

gilles-peskine-arm commented

2019-11-05 08:39:55 -06:00

(Migrated from github.com)

These changes were previously applied to Mbed TLS 2.7, 2.16 and development (released in 2.19), but got lost during the split of Mbed TLS and Mbed Crypto. This is a straightforward side-port of https://github.com/ARMmbed/mbedtls-restricted/pull/503 and https://github.com/ARMmbed/mbedtls-restricted/pull/508 (private links: these were pull requests for a security fix which was quarantined until release).

Fix ARMmbed/mbedtls#1028

Internal ref: IOTCRYPT-969

When writing a private EC key, use a constant size for the private value, as specified in RFC 5915. Previously, the value was written as an ASN.1 INTEGER, which caused the size of the key to leak about 1 bit of information on average and could cause the value to be 1 byte too large for the output buffer. These changes were previously applied to Mbed TLS 2.7, 2.16 and development (released in 2.19), but got lost during the split of Mbed TLS and Mbed Crypto. This is a straightforward side-port of https://github.com/ARMmbed/mbedtls-restricted/pull/503 and https://github.com/ARMmbed/mbedtls-restricted/pull/508 (private links: these were pull requests for a security fix which was quarantined until release). Fix ARMmbed/mbedtls#1028 Internal ref: IOTCRYPT-969

dgreen-arm (Migrated from github.com) approved these changes

2019-11-07 10:25:53 -06:00

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