PART VI

CCM MARK 1

601. GENERAL.

(a) The Combined Cipher Machine Mark 1 (CSP 1600) is a device which converts the ECM Mark 2 to the cryptographic equivalent of the CCM. The CCM Mark 1 is a unit similar to the ECM Mark 2 Cipher Unit. All alterations and modifications are contained within the unit and no change in the ECM Mark 2 is necessary except to insert CSP 1600 into the machine in place of CSP 887.

602. CODE WHEELS.

(a) The Code Wheels used with CSP 1600 are similar to those used with the ECM Mark 2 except that cam-contours have been cut at irregular intervals on the periphery of each face for the purpose of actuating the Stepping Magnet Contacts, and the cam lobes have been ground off.

603. DESCRIPTION.

(a) The unit is so constructed that only five Code Wheels of the set are used at a time. These Code Wheels (together with the connections established through the plunger contacts) form the Alphabet Maze.

(b) Four Stepping Magnet Contact Operating Arms and associated Contacts are included in the unit Their function is to control the stepping of the Code Wheels. Each Contact Operating Arm in so positioned that the nose of the Contact Arm rides the periphery of a Code Wheel. As the Code Wheel is turned, the nose drops into a cam-contour thus closing the contact. When the nose rides the periphery of a Code Wheel the contact is held open. The Code Wheel controlled by this contact will step in accordance with the cam-contours on the controlling Code Wheel

(c) Stepping Circuit connections are established for the circuits of the machine through two plunger contacts on the right end plate of the former Stepping Maze and through five plunger contacts of the former Index Maze.

604. STEPPING CONTROL.

(a) The Code Wheels are stepped as follows:

(b) The Stepping Control thus originates with the center Code Wheel and progresses to each side.

(c) The ECM Mark 2 prints and then steps whereas some machines cryptographically equivalent step and then print This requires an additional "Blank" step when using the CCM Mark 1 after each manual alignment of the Code Wheels in order to bring the machine into proper step On encipherment, the Controller is set at "R" (Reset) when depressing the "Blank" key, and then set at "E" (Encipher) in order that the first letter of the encipherment will be the initial letter of the first five letter group

(a) The ECM Mark 2 is prepared for operation in the normal manner, except that CSP 887 Is replaced by CSP 1600 and associated Code Wheels.

606. KEY LIST.

(a) Each CCM Key List contains:

(1) The Code Wheel Arrangement.

(2) The 26-30 Letter Check.

(3) One or more Initial Code Wheel Alignments.

(b) The following illustrations are examples of the two CCM Key Setting Forms most generally used. They are based on CSP 1811.

(1) For U.S. Navy use:

(2) For Combined (United States - British use):

(c) The Code Wheel Arrangement consists of five numbers corresponding to the numbers engraved on the Code Wheels. Any letter prefixes or suffixes of the individual Code Wheel designations are omitted and in some Key Lists only the final digit may be shown.

(d) The 26-30 Letter Check is given as a means of checking the Code Wheel Arrangement and the operation of the machine.

(e) The Initial Code Wheel Alignment is provided for encipherment of the Message Code Wheel Alignment. Para. (b) (1) Illustrates a Key Setting designed for U. S. Navy use only, and gives three Initial Code Wheel Alignments, designated "SEC", "CON" and "RES" to be used for SECRET, CONFIDENTIAL and RESTRICTED messages respectively. Para. (b) (2) illustrates a Key Setting designed for Combined use, and gives two Initial Code Wheel Alignments, designated "A" and "B" respectively. The Key List in use will define, by means of a footnote, the classifications of messages for which "A" and "B" are to be used.

607. DEFINITIONS.

(a) In this method of operation, two different Code Wheel Alignments are used, requiring differentiation.

(b) The INTERNAL INDICATOR is the encipherment of the Message Code Wheel Alignment, using the Initial Code Wheel Alignment at the beginning of the encipherment

608. CODE WHEEL ARRANGEMENT.

(a) Remove CSP 1600 from its metal box by unscrewing the four thumb screws.

NOTE: CSP 887 may be stowed in the metal box while CSP 1600 is in use.

(b) Determine the proper set of Code Wheels to be used. Each Key List contains this information in the Instructions. Choose the Key Setting corresponding to the date of the Date/Time Group to be used in the message. Insert the Code Wheels in CSP 1600 in accordance with the Code Wheel Arrangement given in the Key Setting.

609. 26-30 LETTER CHECK.

(a) The 26-30 Letter Check is provided for checking the Code Wheel Arrangement and operation of the machine. The five letter group given is the encipherment of the letter "A" on the 26th to 30th steps inclusive using the Code Wheel Arrangement given in the Key Setting with an Initial Code Wheel Alignment of "OOOOO".

(b) To make the 26-30 Letter Check:

(c) If the correct 26-30 Letter Check is not produced see pars. 308(d).

610. ENCIPHERMENT.

(a) Having arranged the Code Wheels in accordance with the Key Setting and having made the 26-30 Letter Check:

611. CHECK DECIPHERMENT.

(a) As a check on accuracy, an enciphered message shall be check-deciphered prior to transmission, preferably by another coding officer, and if available, on a second machine using a different set of Code Wheels. In an emergency the check-decipherment may be deferred until after transmission, but should be completed as soon as possible. THE CHECK-DECIPHERMENT IS MANDATORY.

(a) The following example represents the appearance of a message enciphered in this manner. It is based on the sample Key Setting shown in para. 606 (b) (2). It is assumed PABOC is the CONFIDENTIAL External Indicator.

613. MESSAGE LENGTH.

(a) Very long messages to be enciphered with the CCM Mark 1 should be broken up into parts, each of which uses a different Message Code Wheel Alignment. Each part should not exceed two-hundred (200) groups in length.

614. DECIPHERMENT.

(a) Using the Code Wheel Arrangement of the Key Setting as determined by the Date/Time Group, prepare the machine for operation. Make the 26-30 Letter Check.

(b) If any plain text is desired, set the Controller at "P" (Plain) and set the Zeroizer at "Operate". When using CSP 1600, the Zeroizer is set at "Operate" for all operations.

(c) Select from the Key Setting, the appropriate Initial Code Wheel Alignment for the classification of the message and set the Code Wheels, by hand, to the reference lines in accordance with the designated letters. Set the Controller at "R" (Reset) and, by means of the "Blank" key, step the Code Wheels once. Set the Controller at "D" (Decipher). Disregard the External Indicator, and type (decipher) the Internal Indicator (the second and next-to-the-last groups of the message). This decipherment produces the MESSAGE CODE WHEEL ALIGNMENT.

(d) Set the Code Wheels, by hand, to the Message Code Wheel Alignment, just obtained. Set the Controller at "R" (Reset), and by means of the "Blank" key, step the Code Wheels once.

(e) Set the Controller at "D" (Decipher), and reset the Counter to zero. Type (decipher) the text of the message.

615. CLEARING GARBLES.

(a) If the letters of the Internal Indicator at the beginning and end of the message are not identical (due to errors of transmission) try the various combinations until a Message Code Wheel Alignment Is obtained that will give intelligible text.

(b) The External Indicator of one classification may have been used in the message whereas, an Initial Code Wheel Alignment of another classification may have been erroneously employed.

(c) On decipherment if an "X" appears as a letter of the Message Code Wheel Alignment and the message does not "break" try substituting a "Z" for the "X".

(d) On decipherment, if a blank space appears as a letter of the Message Code Wheel Alignment, try substituting a "Z" for the blank spaces.

ADJUSTMENTS

616. STEPPING MAGNET CONTACTS.

(a) Plate 13 illustrates the action of a Contact Operating Arm as controlled by the Cam-contours of the Code Wheel. Plate 13A shows the nose of the Contact Operating Arm resting in a cam-contour, permitting the contact to close, and Plate 13B shows the nose of the Contact Operating Arm "riding" the periphery of the Code Wheel, holding the Contact open.

611. CONTACT ADJUSTMENTS.

(a) To check the adjustment of the Stepping Magnet Contacts:

(1) Rotate the Code Wheel until the nose of the Contact Arm is on the periphery of the Code Wheel. If necessary, bend the lower contact spring until the contact is "just open".

(2) Rotate the Code Wheel until the nose of the Contact Operating Arm drops into a Cam-contour. It should require only slight pressure to break the contact between the upper and lower contact springs. Adjust by bending the upper contact spring. The nose of the contact arm should clear the bottom of the cam-contour and the push-end of the contact operating arm should "barely clear" the upper Contact spring insulator. This adjustment is made by turning the adjustment screw.

CONFIDENTIAL

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