GM/T 0091-2020 in English

VALID

Password-based key derivation specification

Issued on:2020-12-28
Implemented on:2021-07-01
File Format:PDF
Delivery:Via email within 1~3 business days

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Standard No:	GM/T 0091-2020
Document status:	VALID
Title in English:	Password-based key derivation specification
Title in Chinese:	基于口令的密钥派生规范
Language:	English
File Format:	Electronic (PDF)
Delivery:	Via email within 1~3 business days
Issued on:	2020-12-28
Implemented on:	2021-07-01
ICS Classification:	35.040-Character sets and information coding
Chinese Classification:	L80-Data encryption
Related Keywords:	password-based key derivation specification introduction analysis key length technical module core algorithm security parameters key derivation function bytes key technology implementation points key derivation function implementation pbkdf2 core calculation formula
Related Topics:	make key gm t gm/t password key GM/T 38636-2020 OceanView1.6.7 product key cpcif 0091

本标准规定了基于口令的密钥派生规范，包括基于口令的密钥派生函数、基于口令的加密方案、基于口令的消息鉴别码。
本标准适用于证书与密钥迁移时利用口令来保护被迁移的密钥。

Introduction

Analysis of the standard technical framework

This standard builds a complete password-based cryptographic system, which includes three major technical modules:

Technical module	Core algorithm	Security parameters
Key derivation function (PBKDF)	HMAC-SM3	Number of iterations ≥ 1024, salt value ≥ 8 bytes
Encryption scheme (PBES)	SM4-CBC	IV length 16 bytes, PKCS#7 padding
Message authentication code (PBMAC)	HMAC-SM3	Output length: 32 bytes

Key Technology Implementation Points

1. Key Derivation Function Implementation

PBKDF2 core calculation formula: DK = F(P,S,c,1) || F(P,S,c,2) || ... || F(P,S,c,n)

Wherein, the F function is implemented through HMAC-SM3 iteration:

F(P,S,c,i) = U1 ⊕ U2 ⊕ ... ⊕ Uc U1 = PRF(P, S || INT(i)) U2 = PRF(P, U1) ...

2. Encryption Scheme Implementation

SM4-CBC encryption process:

Generate derived key: DK = KDF(P,S,c,dkLen)
Message padding: Use PKCS#7 standard to fill to multiple of 16 bytes
CBC mode encryption: IV is recommended to be derived through KDF

Security Enhancement Measures

Salt Value Configuration Specifications

Application Scenarios	Salt Value Requirements	Example
Normal encryption	Random 64 bits or more	Hardware random number generation
Key reuse prevention	Include operation type identifier	0x01\|Random number

Implementation recommendations

Parameter selection guide

Number of iterations: ≥10000 for general applications, ≥10,000,000 for high-security scenarios
Derived key length: 128 bits for SM4 encryption and 256 bits for HMAC-SM3
Salt management: Different operations should use independent salt spaces

Avoidance of typical errors

Case: A system uses a fixed salt value, resulting in predictable keys
Solution: Use the salt generation strategy recommended in Appendix A.1 to ensure that the salt value is unique for each operation

More samples: QC/T 942-2021 DL/T 5154-2012 DL/T 368-2010

Sample only — not a preview of GM/T 0091-2020