How to use the command 'gmssl' (with examples)

GmSSL is a crypto toolkit that provides support for various cryptographic algorithms such as SM1, SM2, SM3, SM4, SM9, and ZUC/ZUC256. It can be used to perform various cryptographic operations like hashing, encryption, decryption, and key generation.

Use case 1: Generate an SM3 hash for a file

Code:

gmssl sm3 path/to/file

Motivation: Generating a hash for a file allows us to verify the integrity of the file, as even a slight change in the content of the file will result in a completely different hash value.

Explanation:

• gmssl - the command-line tool for GmSSL
• sm3 - specifies the hash algorithm to use (SM3)
• path/to/file - the path to the file for which the hash needs to be generated

Example output:

Hash for 'path/to/file':
6cb5f01437860b6f4e22e26f66bd6e5b5064ff2d8817010a9978834b444d3c21

Use case 2: Encrypt a file using the SM4 cipher

Code:

gmssl sms4 -e -in path/to/file -out path/to/file.sms4

Motivation: Encryption protects sensitive information from unauthorized access by converting it into an unreadable format.

Explanation:

• gmssl - the command-line tool for GmSSL
• sms4 - specifies the cipher algorithm to use (SM4)
• -e - indicates encryption mode
• -in path/to/file - the path to the file to be encrypted
• -out path/to/file.sms4 - the path where the encrypted file will be saved

Use case 3: Decrypt a file using the SM4 cipher

Code:

gmssl sms4 -d -in path/to/file.sms4

Motivation: Decrypting a file allows us to retrieve the original content that was encrypted, enabling access to the sensitive information.

Explanation:

• gmssl - the command-line tool for GmSSL
• sms4 - specifies the cipher algorithm to use (SM4)
• -d - indicates decryption mode
• -in path/to/file.sms4 - the path to the file to be decrypted

Use case 4: Generate an SM2 private key

Code:

gmssl sm2 -genkey -out path/to/file.pem

Motivation: The SM2 algorithm is used for key generation, and having a private key is essential for signing, encryption, and other cryptographic operations.

Explanation:

• gmssl - the command-line tool for GmSSL
• sm2 - specifies the cryptographic algorithm to use (SM2)
• -genkey - generates an SM2 private key
• -out path/to/file.pem - the path to the file where the private key will be saved (in PEM format)

Use case 5: Generate an SM2 public key from an existing private key

Code:

gmssl sm2 -pubout -in path/to/file.pem -out path/to/file.pem.pub

Motivation: The public key is used for verifying signatures and performing other cryptographic operations between parties possessing the corresponding private key.

Explanation:

• gmssl - the command-line tool for GmSSL
• sm2 - specifies the cryptographic algorithm to use (SM2)
• -pubout - generates the corresponding public key from an existing private key
• -in path/to/file.pem - the path to the input private key file
• -out path/to/file.pem.pub - the path to the output public key file (in PEM format)

Use case 6: Encrypt a file using the ZUC cipher

Code:

gmssl zuc -e -in path/to/file -out path/to/file.zuc

Motivation: The ZUC cipher is utilized for encrypting data, providing confidentiality for the contents of the file.

Explanation:

• gmssl - the command-line tool for GmSSL
• zuc - specifies the cipher algorithm to use (ZUC)
• -e - indicates encryption mode
• -in path/to/file - the path to the file to be encrypted
• -out path/to/file.zuc - the path where the encrypted file will be saved

Use case 7: Decrypt a file using the ZUC cipher

Code:

gmssl zuc -d -in path/to/file.zuc

Motivation: Decrypting a file encrypted using the ZUC cipher allows us to obtain the original content of the file.

Explanation:

• gmssl - the command-line tool for GmSSL
• zuc - specifies the cipher algorithm to use (ZUC)
• -d - indicates decryption mode
• -in path/to/file.zuc - the path to the file to be decrypted

Use case 8: Print version

Code:

gmssl version

Motivation: Printing the version of GmSSL helps to identify the installed version and confirm the availability of specific features.

Explanation:

• gmssl - the command-line tool for GmSSL
• version - prints the version information of GmSSL

Example output:

GmSSL 3.0.3

Conclusion:

The gmssl command-line tool provides a wide range of capabilities for performing cryptographic operations using various algorithms. These examples demonstrate different use cases such as hashing, encryption, decryption, and key generation. By understanding and utilizing these use cases, developers and security professionals can enhance the security of their systems and protect sensitive information from unauthorized access.