digest ';' ALGORITHM ';' FILE

Summary

The digest macro computes a cryptographic hash of a file using a specified algorithm (such as MD5, SHA-1, SHA-256, etc.). The result is returned as a hexadecimal string.

Syntax

${digest;<algorithm>;<file>}

Parameters

• algorithm - The digest algorithm name (e.g., “MD5”, “SHA-1”, “SHA-256”, “SHA-512”)
• file - Path to the file to hash (relative to project directory)

Behavior

• Reads the entire file and computes its digest
• Uses Java’s MessageDigest API, so any supported algorithm can be used
• Returns the digest as a lowercase hexadecimal string
• File path is resolved relative to the project directory
• Throws an exception if the algorithm is not supported or file cannot be read

Examples

Calculate MD5 hash:

file.md5=${digest;MD5;target/mybundle.jar}

Calculate SHA-256 hash:

file.sha256=${digest;SHA-256;LICENSE.txt}

Calculate SHA-512 for verification:

Bundle-Digest-SHA512: ${digest;SHA-512;${@}}

Multiple checksums:

md5.checksum=${digest;MD5;artifact.jar}
sha1.checksum=${digest;SHA-1;artifact.jar}
sha256.checksum=${digest;SHA-256;artifact.jar}

Use Cases

• Generating checksums for artifact verification
• Creating file integrity manifests
• Implementing build reproducibility checks
• Generating unique identifiers based on file content
• Security verification and tamper detection
• Creating content-addressable storage keys

Notes

• Common algorithms include: MD5, SHA-1, SHA-256, SHA-384, SHA-512
• The algorithm name is case-insensitive
• MD5 and SHA-1 are considered weak for security purposes; prefer SHA-256 or stronger
• The output is always lowercase hexadecimal
• For large files, this reads the entire file into memory for hashing
• See also: ${md5} and ${sha1} macros for specific algorithms

See test cases in MacroTestsForDocsExamples.java