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feat: improve flag format

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This commit is contained in:
Michael
2026-05-08 00:30:28 +02:00
parent 5ec7d85b4e
commit 6f7de5d8b5
3 changed files with 8 additions and 7 deletions
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2
.env.example
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@@ -1,2 +1,2 @@
FLAG_LEN=32 FLAG_LEN=32
FLAG_PREFIX=ctf FLAG_FORMAT=ctf{FLAG_GOES_HERE}

2
Makefile
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@@ -56,7 +56,7 @@ $(EMU_OBJ): $(EMU_OBJ_FILES) | build
$(GENERATED): .FORCE $(GENERATED): .FORCE
mkdir -p $(dir $@) mkdir -p $(dir $@)
python codegen/generate.py $(FLAG_PREFIX) $(FLAG_LEN) > $@ python codegen/generate.py $(FLAG_FORMAT) $(FLAG_LEN) > $@
build: build:

11
codegen/generate.py
View File

@@ -47,17 +47,18 @@ def get_check_code(flag_part, user_part, c_mangler):
def main(): def main():
if len(sys.argv) != 3: if len(sys.argv) != 3:
eprint(f"Usage: {sys.argv[0]} <flag_prefix> <flag_length>") eprint(f"Usage: {sys.argv[0]} <flag_format> <flag_length>")
exit(1) exit(1)
# Flag prefix is not used, currently the flag is just used as-is # Flag prefix is not used, currently the flag is just used as-is
flag_prefix = sys.argv[1] flag_format = sys.argv[1]
flag_len = int(sys.argv[2]) flag_len = int(sys.argv[2])
eprint(f"Generating flag with prefix {flag_prefix} and length {flag_len}")
# Generate a secret # Generate a secret
secret = secrets.token_hex(flag_len) secret = secrets.token_urlsafe(flag_len)
secret = flag_format.replace("FLAG_GOES_HERE", secret)
eprint(f"Generated Flag: {secret}")
# Change the bytes of the secret # Change the bytes of the secret
mangled_secret, c_manglers = mangle(secret) mangled_secret, c_manglers = mangle(secret)