Online SHA-1 Hash Generator (Supports HMAC)

Input String

HMAC Key (Optional)

Output Format:

Lowercase (40 characters)

Uppercase (40 characters)

SHA-1 Hash Value

Tool Description

SHA-1 (Secure Hash Algorithm 1) is a cryptographic hash function that maps data of any length to a fixed 160-bit (40 hexadecimal character) hash value. It was widely used in various security protocols such as TLS/SSL, PGP, SSH, IPsec, and the popular version control system Git.

Security Warning

Since 2005, the security of SHA-1 has been seriously questioned, and practical collision attacks have been demonstrated. Since 2017, major browsers no longer trust SHA-1 certificates. For new security applications, **SHA-256 or stronger algorithms are strongly recommended**.

Standard SHA-1: Perform standard SHA-1 hash calculation on the input string.
HMAC-SHA1: If a key is provided, the tool will calculate a Hash-based Message Authentication Code (HMAC) for data integrity verification and message authentication.
Native Implementation: This tool uses the browser's built-in `SubtleCrypto` API, requiring no third-party libraries—secure and efficient.