In PostgreSQL, passwords are often stored as MD5-hashed values. When creating a user, PostgreSQL can store the password in MD5 format, which is a cryptographic hash of the password concatenated with the string postgres. The format looks like this:
bash
MD5<md5_hash_of_password + 'postgres'>
This means that the MD5 hash of the actual password (e.g., "mysecretpassword") is calculated, and then the string postgres is appended to it before hashing.
PostgreSQL MD5 Password Generator
To generate an MD5 password hash for use with PostgreSQL, you'll need to concatenate the password with the string "postgres" and then compute the MD5 hash of the result. The format is as follows:
bash
MD5<md5_hash_of_password + 'postgres'>
Python Script to Generate PostgreSQL MD5 Password Hash:
Here's a Python script that generates the MD5 hash for a given password in PostgreSQL-compatible format:
python
import hashlib
def generate_postgresql_md5_password(password):
"""Generate an MD5 password hash compatible with PostgreSQL."""
# Concatenate the password with 'postgres' (which is required by PostgreSQL)
password_with_salt = password + 'postgres'
# Calculate the MD5 hash of the concatenated string
md5_hash = hashlib.md5(password_with_salt.encode()).hexdigest()
# Format it as PostgreSQL MD5 password
postgresql_md5_password = 'MD5' + md5_hash
return postgresql_md5_password
# Example usage:
password = "mysecretpassword" # The password you want to hash
md5_password = generate_postgresql_md5_password(password)
print("PostgreSQL MD5 Password:", md5_password)
Explanation:
Concatenate Password: We append the string 'postgres' to the user's password. This is because PostgreSQL creates the MD5 hash by combining the user password with 'postgres'.
Hash the Concatenated String: The hashlib.md5() function computes the MD5 hash of the concatenated string (password + 'postgres').
Generate the MD5 Password: The MD5 hash is prefixed with MD5 to match the PostgreSQL password format.
Example Output:
For a password like "mysecretpassword", the output will look something like this:
wasm
PostgreSQL MD5 Password: MD5e2fc714c4727ee9395f324cd2e7b4f8d
Example Use in PostgreSQL:
Once you have generated the MD5 password hash, you can use it to create a PostgreSQL user. For example:
sql
CREATE USER new_user WITH PASSWORD 'MD5e2fc714c4727ee9395f324cd2e7b4f8d';
Important Notes:
Security: MD5 is no longer considered a secure hashing algorithm. If possible, use more secure methods like SCRAM-SHA-256, which PostgreSQL supports as well.
Why MD5 with postgres?: PostgreSQL uses this MD5-based scheme for compatibility reasons. It hashes the password along with the string 'postgres' to create a hash that can be stored in the database.
Password Length and Complexity: Ensure your password is sufficiently long and complex to prevent brute-force attacks.