ctf_aria

write up ctf by ariafatah

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Project maintained by ariafatah0711 Hosted on GitHub Pages — Theme by mattgraham

soal

—–BEGIN RSA PRIVATE KEY—–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—–END RSA PRIVATE KEY—–

Public key = md5(base64 blob only) MD5 2 first bytes are 0x42f5

setup

cat > private.key << EOF
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
EOF

solve

openssl rsa -in private.key -out pub -pubout 
# writing RSA key

cat pub
# -----BEGIN PUBLIC KEY-----
# MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDwkrxVrZ+KCl1cX27SHDI7Efgn
# FJZ0qTHUD6uEeSoZsiVkcu0/XOPbz1RtpK7xxpKMSnH6uDc5On1IEw3A127wW4Y3
# Lqqwcuhgypd3Sf/bH3z4tC25eqr5gA1sCwSaEw+yBxdnElBNOXxOQsST7aZGDyIU
# tmpouI1IXqxjrDx2SQIDAQAB
# -----END PUBLIC KEY-----

cat pub | tail -n 5 | head -n 4
# MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDwkrxVrZ+KCl1cX27SHDI7Efgn
# FJZ0qTHUD6uEeSoZsiVkcu0/XOPbz1RtpK7xxpKMSnH6uDc5On1IEw3A127wW4Y3
# Lqqwcuhgypd3Sf/bH3z4tC25eqr5gA1sCwSaEw+yBxdnElBNOXxOQsST7aZGDyIU
# tmpouI1IXqxjrDx2SQIDAQAB


cat pub | tail -n 5 | head -n 4 | tr -d "\n"
# MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDwkrxVrZ+KCl1cX27SHDI7EfgnFJZ0qTHUD6uEeSoZsiVkcu0/XOPbz1RtpK7xxpKMSnH6uDc5On1IEw3A127wW4Y3Lqqwcuhgypd3Sf/bH3z4tC25eqr5gA1sCwSaEw+yBxdnElBNOXxOQsST7aZGDyIUtmpouI1IXqxjrDx2SQIDAQAB

cat pub | tail -n 5 | head -n 4 | tr -d "\n" | md5sum > out 

cat out 
# 42f51df8b6a2bafa824c179a38066e5d  -

## input key in the ringzer0, and submit
42f51df8b6a2bafa824c179a38066e5d
FLAG-9869O2dQ43d1r116kfD0Sj5n

flag

FLAG-9869O2dQ43d1r116kfD0Sj5n