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feat: Support legacy, pre-OpenPGP packet format (#44)
Support legacy packet format for compatibility with GnuPG. Closes: #43 Signed-off-by: Jagoda Ślązak <jslazak@jslazak.com>
This commit is contained in:
Jagoda Estera Ślązak
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GitHub
GitHub
parent
c1f728535f
commit
cc1604b0b2
+130
-37
@@ -23,48 +23,122 @@ macro_rules! get_byte {
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///
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/// Returns an [`error::Error::TruncatedHeader`] if the OpenPGP packet header is truncated.
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fn check_openpgp_payload(payload: &[u8]) -> Result<bool, error::Error> {
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// From RFC9580; we have to support legacy format too, for compatibility with GnuPG.
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//
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// +---------------+
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// Encoded Packet Type ID: |7 6 5 4 3 2 1 0|
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// +---------------+
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// OpenPGP format:
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// Bit 7 -- always one
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// Bit 6 -- always one
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// Bits 5 to 0 -- Packet Type ID
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//
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// Legacy format:
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// Bit 7 -- always one
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// Bit 6 -- always zero
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// Bits 5 to 2 -- Packet Type ID
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// Bits 1 to 0 -- length-type
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let mut i: usize = 0;
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while i < payload.len() {
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// Only OpenPGP format is allowed.
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if (get_byte!(payload, i) & 0xC0) != 0xC0 {
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log::debug!("check_openpgp_payload: i={i} Not OpenPGP format");
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return Ok(false);
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}
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let packet_type_id = get_byte!(payload, i) & 0x3F;
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i += 1;
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while get_byte!(payload, i) >= 224 && get_byte!(payload, i) < 255 {
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// Partial body length.
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let partial_length = 1usize << (get_byte!(payload, i) & 0x1F);
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i += 1 + partial_length;
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}
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let body_len: usize;
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if get_byte!(payload, i) < 192 {
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// One-octet length.
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body_len = get_byte!(payload, i) as usize;
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i += 1;
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} else if get_byte!(payload, i) < 224 {
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// Two-octet length.
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body_len = (((get_byte!(payload, i) as usize) - 192) << 8)
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+ (get_byte!(payload, i + 1) as usize)
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+ 192;
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i += 2;
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} else if get_byte!(payload, i) == 255 {
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// Five-octet length.
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body_len = ((get_byte!(payload, i + 1) as usize) << 24)
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| ((get_byte!(payload, i + 2) as usize) << 16)
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| ((get_byte!(payload, i + 3) as usize) << 8)
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| (get_byte!(payload, i + 4) as usize);
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i += 5;
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let bits_7_6 = get_byte!(payload, i) & 0xC0;
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// bit 6 is 0 for legacy (GnuPG)
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let legacy = if bits_7_6 == 0xC0 {
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false
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} else if bits_7_6 == 0x80 {
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true
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} else {
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// Impossible, partial body length was processed above.
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log::debug!("check_openpgp_payload: i={i} Invalid body length");
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log::debug!(
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"check_openpgp_payload: i={i} bits 7 and 6 doesn't indicate OpenPGP or legacy format"
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);
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return Ok(false);
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}
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};
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i += body_len;
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let packet_type_id = if legacy {
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// bits 5 to 2
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(get_byte!(payload, i) & 0x3C) >> 2
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} else {
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// bits 5 to 0
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get_byte!(payload, i) & 0x3F
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};
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if legacy {
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// Body length calculation - Legacy, RFC9580 4.2.2
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let length_type = get_byte!(payload, i) & 0x03;
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i += 1;
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let body_len: usize;
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match length_type {
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0 => {
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// One-octet length.
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body_len = get_byte!(payload, i) as usize;
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i += 1;
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}
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1 => {
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// Two-octet length.
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body_len = ((get_byte!(payload, i) as usize) << 8)
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+ (get_byte!(payload, i + 1) as usize);
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i += 2;
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}
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2 => {
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// Four-octet length.
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body_len = ((get_byte!(payload, i) as usize) << 24)
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+ ((get_byte!(payload, i + 1) as usize) << 16)
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+ ((get_byte!(payload, i + 2) as usize) << 8)
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+ (get_byte!(payload, i + 3) as usize);
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i += 4;
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}
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// 3 - indeterminate length, not supported
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// RFC9580 4.2.2:
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// "An implementation MUST NOT generate a Legacy format packet with indeterminate length."
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// We hope they don't.
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_ => {
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log::debug!(
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"check_openpgp_payload: i={i} Indeterminate length (3) length-type in legacy packet format"
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);
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return Ok(false);
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}
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};
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i += body_len;
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} else {
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// Body length calculation - OpenPGP, RFC9580 4.2.1
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i += 1;
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while get_byte!(payload, i) >= 224 && get_byte!(payload, i) < 255 {
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// Partial body length.
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let partial_length = 1usize << (get_byte!(payload, i) & 0x1F);
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i += 1 + partial_length;
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}
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let body_len: usize;
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if get_byte!(payload, i) < 192 {
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// One-octet length.
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body_len = get_byte!(payload, i) as usize;
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i += 1;
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} else if get_byte!(payload, i) < 224 {
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// Two-octet length.
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body_len = (((get_byte!(payload, i) as usize) - 192) << 8)
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+ (get_byte!(payload, i + 1) as usize)
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+ 192;
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i += 2;
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} else if get_byte!(payload, i) == 255 {
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// Five-octet length.
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body_len = ((get_byte!(payload, i + 1) as usize) << 24)
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| ((get_byte!(payload, i + 2) as usize) << 16)
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| ((get_byte!(payload, i + 3) as usize) << 8)
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| (get_byte!(payload, i + 4) as usize);
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i += 5;
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} else {
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// Impossible, partial body length was processed above.
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log::debug!("check_openpgp_payload: i={i} Invalid body length");
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return Ok(false);
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}
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i += body_len;
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}
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if i == payload.len() {
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// Last packet should be
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@@ -168,6 +242,25 @@ uj3GwEFrHS+Xuf2UDgpszYT3hI2cL/kUtGakVR7m7vVMZqXBUbZdGAEb1PZNPwsI
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E4aMK02+EVB+tSN4Fzj99N2YD0inVYt+oPjr2tHhUS6aSGBNS/48Ki47DOg4Sxkn
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lkOWnEbCD+XTnbDd
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=agR5
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-----END PGP MESSAGE-----"#, (true, true))]
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// GnuPG uses a legacy packet format that was obsoleted back in 1998 (RFC2440);
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// despite RFC9580 stating "The Legacy packet format SHOULD NOT be used to generate new data".
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#[case::gnupg(r#"-----BEGIN PGP MESSAGE-----
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hF4DFYw3E47UG/ASAQdA3JnkJLJJALitYG/jzzEuF0p+hEBsgLTicaEJkJerInkw
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SftuCMBjxv4D6rTqNkBn7IQh6gmlUKrUNBVEnq0V1InVF9o0kDpZfUUaB5ajNDMb
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hF4DMiMKov7/CVgSAQdA7ib6HK7UVW2IdAM5PILbtqzuynukooXdg9YWWamjal8w
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h/L0BxbtUFzI3U847dvzwtsW7A9CZXpi45OMXRC9mO3G/FAY1fW+C6PwObT7X1qK
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0sDSAbyYddCihL1UEl6EigtD/YQezCTCydzstD2cRdV75lmUqzMCR8NbfvdttBbl
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g04ZZtoHm1DSnXIAN4iFzW4EBgNVUDCnqO8wyYmWw4OCOt45IkTXGQUICGxeVh6g
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4Pdj4OzSrg/mTZGIDjE2h/osVpPEQjwcAus73EZC4sz4n2U+OMHsq0M54Ds7wyGv
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1KBzcQQ5Rc/DPPT0INnl58datm2HGKtWFWYab9/cw/fnQ+oYhmpkZbdITTmnTAyn
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CHih86i0w6gXsX99iRLe6yP8BcU3rCCflsCp5zzlcFYViTPgEn1W8H32VOXulfcV
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rpRFtc5yzjFj8Dvq9gI9yGIgqiS7oEAXdRBYhmBRTydMcbS1bCPDWy5w95Cp2VzR
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x8cBq5e+27QTl9YNHr4xeric7del79wktJFiINzUCQPwkwM9ud2EJ1zN8Owr2Dp8
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JvS2ioSEK5J2Lc95vDLmbVnMuKmVW6qD+fEdtYSHnSIc/t+iYG3GlaFyvO8t0Jav
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cbsijrbYhoSOq67KseQWvfL+gL5u
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=WWqc
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-----END PGP MESSAGE-----"#, (true, true))]
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#[case::with_comment(r#"-----BEGIN PGP MESSAGE-----
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Version: 1
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