When working with encrypted RSA private keys, developers often encounter two distinct error patterns:

// Classic bad passphrase error
openssl rsa -in encrypted.key
Enter pass phrase for encrypted.key:
unable to load Private Key
error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt

// The more puzzling ASN1 error
openssl rsa -in encrypted.key
Enter pass phrase for encrypted.key:
unable to load Private Key
error:0D07207B:asn1 encoding routines:ASN1_get_object:header too long
error:0D068066:asn1 encoding routines:ASN1_CHECK_TLEN:bad object header

The ASN1 header errors typically indicate one of several scenarios:

• The key file is corrupted (partial or malformed)
• The encryption format doesn't match what OpenSSL expects
• The key was generated with non-standard parameters

First, verify your key's basic structure:

file id_rsa
# Should return something like:
# id_rsa: PEM RSA private key

For a more thorough check:

openssl asn1parse -in id_rsa
# This helps identify where the ASN1 parsing fails

Option 1: Try alternative OpenSSL commands

# For PKCS#8 format
openssl pkcs8 -in id_rsa -topk8 -out id_rsa.decrypted

# For traditional PEM
openssl rsa -in id_rsa -out id_rsa.decrypted -traditional

Option 2: Reconstruct the key header

If the key has malformed headers, try adding standard PEM boundaries:

-----BEGIN RSA PRIVATE KEY-----
[your base64 key data]
-----END RSA PRIVATE KEY-----

When standard methods fail, consider these approaches:

# Attempt to extract raw ASN1 data
openssl asn1parse -in id_rsa -dump -strict

# Try parsing with different versions of OpenSSL
openssl1.0 rsa -in id_rsa -out id_rsa.decrypted

# Use ssh-keygen as an alternative
ssh-keygen -p -f id_rsa -m PEM

Remember that key corruption might require recreating the keypair if recovery attempts fail.

• Always back up keys in multiple formats (PEM, PKCS8, DER)
• Verify keys immediately after generation
• Consider using key management systems for critical infrastructure

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When dealing with encrypted RSA private keys, we typically encounter two distinct error patterns:

# Classic bad passphrase error
openssl rsa -in encrypted.key
Enter pass phrase for encrypted.key:
unable to load Private Key
140256774473360:error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt

# The more puzzling ASN1 error
openssl rsa -in encrypted.key
Enter pass phrase for encrypted.key:
unable to load Private Key
139662870623888:error:0D07207B:asn1 encoding routines:ASN1_get_object:header too long

Before attempting fixes, verify the key's basic structure:

# Check if the file contains BEGIN/END markers
grep -e "BEGIN" -e "END" id_rsa

# Verify basic ASN1 structure
openssl asn1parse -in id_rsa

The "header too long" ASN1 error typically indicates:

• File corruption during transfer (especially FTP in binary/text mode issues)
• Improper key generation using non-standard tools
• Mixed line endings in the key file
• Incomplete key data (partial transfers)

1. File Sanitization

First ensure proper file formatting:

# Convert DOS to Unix line endings
dos2unix id_rsa

# Remove any trailing whitespace
sed -i 's/[[:space:]]*$//' id_rsa

2. Alternative Decryption Methods

Try different OpenSSL command variants:

# Traditional RSA format
openssl rsa -in id_rsa -out decrypted.key

# PKCS8 format attempt
openssl pkcs8 -topk8 -in id_rsa -out decrypted.key -nocrypt

# Force PEM encoding
openssl rsa -in id_rsa -outform PEM -out decrypted.key

3. Key Reconstruction

If standard methods fail, extract components manually:

# Extract encrypted PEM payload
sed -n '/BEGIN/,/END/p' id_rsa > payload.pem

# Base64 decode the content
openssl base64 -d -in payload.pem -out payload.bin

# Analyze binary structure
hexdump -C payload.bin | head -20

For severely corrupted keys, consider:

# Brute-force ASN1 parsing with different offsets
for i in {0..10}; do
    dd if=id_rsa of=trimmed.key bs=1 skip=$i
    openssl rsa -in trimmed.key -check 2>/dev/null && break
done

• Always generate keys with standard tools: ssh-keygen -t rsa -b 4096
• Use armored format when transferring keys: gpg --armor --export-secret-key
• Verify checksums after transfer: sha256sum id_rsa